The State of Western Australia v Davidson - [2022] WASC 70

JURISDICTION     :   SUPREME COURT OF WESTERN AUSTRALIA
TITLE OF COURT :   THE COURT OF APPEAL (WA)
CITATION:   THE STATE OF WESTERN AUSTRALIA -v- DAVIDSON [2022] WASC 70
CORAM:   MAZZA J
HEARD:   3-9 NOVEMBER 2021 & 8 FEBRUARY 2022
DELIVERED          :   2 MARCH 2022
FILE NO/S:   INS 88 of 2020
BETWEEN:   THE STATE OF WESTERN AUSTRALIA
Prosecution
AND
BRENDAN RICHARD L DAVIDSON
Accused

Catchwords:

Criminal law - Trial by judge alone - Accused charged with one count of, with intent to harm, doing an act as a result of which the life, health or safety of another was, or was likely to be, endangered, and one count of murder - Whether accused is not guilty by reason of unsoundness of mind - Whether the accused's mental impairment deprived him of the capacity to know that he ought not do the act - Whether the accused intentionally caused himself to become intoxicated or stupefied by his consumption of methylamphetamine

Legislation:

Criminal Code (WA), s 26, s 27, s 28, s 268, s 270, s 279, s 304(i)
Criminal Investigation Act 2006 (WA), s 137, s 138
Criminal Procedure Act 2004 (WA), s 118, s 119, s 120
Evidence Act 1906 (WA), s 32

Result:

Verdicts of guilty

Representation:

Counsel:

Prosecution	:	K Robinson & D E Aldous
Accused	:	K J Farley SC

Solicitors:

Prosecution	:	Director of Public Prosecutions (WA)
Accused	:	Legal Aid (WA)

Case(s) referred to in decision(s):

Evans v The State of Western Australia [2010] WASCA 34
R v Clough (No 2) [2010] QCA 120; (2011) Qd R 222
R v Porter [1933] HCA 1; (1933) 55 CLR 182
Stapleton v The Queen [1952] HCA 56; (1952) 86 CLR 358
Stefanski v The State of Western Australia [2022] WASCA 5
The State of Western Australia v Daly [2019] WASC 386
The State of Western Australia v Herbert [2017] WASC 101
The State of Western Australia v Knock [2020] WASC 246
The State of Western Australia v Taylor [2021] WASC 470
Ward v The Queen [2000] WASCA 413; (2000) 23 WAR 254

TABLE OF CONTENTS

General legal principles

Presumption of innocence

The onus of proof

The standard of proof

The verdicts must be based on the evidence

The distinction between credibility and reliability

Witnesses whose statements were read into evidence, special witnesses and video‑link witnesses

Multiple charges

Expert evidence

Mr Davidson did not give evidence

Inferences

Elements of the alleged offences

Insanity - legal principles

Intoxication - applicable legal principles

The facts of the offending

Background

The events of 17 October 2019

The events of 18 October 2019

The post-mortem

The toxicological evidence

Report of Dr Joyce dated 17 May 2021

Evidence of Dr Joyce

Report of Dr Robertson

Evidence of Dr Robertson

Findings from the toxicological evidence

Mr Davidson's psychiatric history

The psychiatric evidence

Report of Dr Adam Brett dated 2 June 2021

Evidence of Dr Brett

Report of Dr Pascu dated 26 June 2020

Evidence of Dr Pascu

The State's case

The accused's case

Did Mr Davidson's mental impairment deprive him of the capacity to know that he ought not do the acts the subject of counts 1 and 2?

Did Mr Davidson intentionally cause himself to become intoxicated or stupefied by methylamphetamine?

Discussion

The issue of intention - count 1

The issue of intention - count 2

Verdicts

MAZZA J:

Mr Davidson is charged on indictment with two offences. Count 1 alleges that, on 17 October 2019, at Mandurah, he, with intent to harm, did an act as a result of which the life, health or safety of Melanie May Ugle was, or was likely to be, endangered. Count 2 alleges that, on 20 October 2019, at Perth, he murdered Mark Robert Stokes. Count 1 is contrary to s 304(2)(b) of the Criminal Code (WA) (the Code). Count 2 is contrary to s 279 of the Code.
On 26 August 2021, Corboy J made an order, pursuant to s 118 of the Criminal Procedure Act 2004 (WA) (the CPA), for a judge alone trial. Mr Davidson's trial took place before me over six sitting days between 3 and 9 November 2021, and on 8 February 2022.
At the commencement of the trial, on arraignment, Mr Davidson entered a plea of not guilty on account of unsoundness of mind to each charge.[1] Immediately after his arraignment, Mr Davidson made the following admissions pursuant to s 32 of the Evidence Act 1906 (WA):[2]
1.That on 17 October 2019 he did an act which endangerd the life, health or safety of Melanie Ugle.
2.That on 17 October 2019, he caused the death of Mark Stokes.
[1] ts 19.
[2] ts 20, exhibit 1.
By the end of the trial, there was no dispute that, at the time Mr Davidson committed the acts which constituted each charge, he was in a state of mental impairment, namely, he was suffering from a mental illness which was either bipolar affective disorder or schizoaffective disorder.[3] The real issues for me to determine are:
(1)Did Mr Davidson's mental impairment deprive him of the capacity to know that he ought not do the act, as provided for in s 27(1) of the Code? Senior counsel for Mr Davidson referred to this issue as being the 'real crux' of the case.[4]
(2)If so, having regard to s 28(2) of the Code, does the defence in s 27(1) not apply because he intentionally caused himself to become intoxicated or stupefied by his consumption of methylamphetamine?
[3] Prosecutor's closing address ts 364; defence closing address ts 407 - 408.
[4] ts 405.

General legal principles

Section 119 of the CPA provides that, in a trial by judge alone, the judge must apply, so far as is practicable, the same principles of law as would be applied in a trial before a jury. If any written or other law requires information or a warning or an instruction to be given to a jury in certain circumstances, or prohibits a warning from being given to a jury in certain circumstances, the judge in a trial by a judge alone must take the requirement or prohibition into account if those circumstances arise in the course of a trial.
Section 120 of the CPA provides that in a trial by judge alone, the judge may make any findings and give any verdict that a jury could have made or given if a trial had been before a jury. Further, the judgment in a trial by judge alone must include the principles of law that have been applied and the findings of fact upon which the judge has relied.
At this point, it is convenient to set out the general principles of law which I have applied. Later in these reasons, I will make the necessary findings of fact.
Putting to one side, for the moment, the legal principles raised by Mr Davidson's pleas of not guilty on account of unsoundness of mind, I have applied the following legal principles.

Presumption of innocence

The starting point is that an accused person such as Mr Davidson is presumed innocent of the charges. This presumption applies unless and until his guilt is established on the evidence to the criminal standard. If guilt is not established, the presumption of innocence remains and the accused must be found not guilty.

The onus of proof

The State having brought the charges against the accused must prove them. The onus or burden of proof lies upon the State from the start of the trial to its end. A person accused of an offence bears no onus.

The standard of proof

The standard of proof to be met by the State is proof beyond reasonable doubt. These words require no explanation. It is enough to say that the standard is the highest known to the law, but this does not mean that it is an impossible standard. It is a higher standard of proof than the civil standard of proof on the balance of probabilities, that is, what is more likely than not.
The standard of proof of beyond reasonable doubt applies to the elements or essential components of each of the charges. It is only if all of the elements of a charge are proved beyond reasonable doubt that the accused can be found guilty. The elements of each of the charges which have been brought against Mr Davidson are set out at [29] and [31] below.
If I am not satisfied that the State has proved all of the elements of a charge beyond reasonable doubt, I must find Mr Davidson not guilty. However, if I am satisfied that the State has proved all of the elements of a charge beyond reasonable doubt, I must find Mr Davidson guilty.

The verdicts must be based on the evidence

The verdicts I reach must be based only on the evidence led at this trial. The evidence in this trial comes from the oral testimony of the witnesses, witness statements which were read into evidence, Mr Davidson's admissions pursuant to s 32 of the Evidence Act and the exhibits which were tendered in the course of the trial. It comes from nowhere else. I cannot engage in speculation or guesswork. A question put to a witness is not evidence unless affirmed by the witness. The opening and closing addresses of counsel are not evidence. Any feelings of prejudice or sympathy, whether towards Mr Stokes, Mr Davidson, their families and friends, or any witness, have no place in the determination of whether Mr Davidson is guilty of the charges. My duty is to decide this case wholly and solely on the evidence and nothing else.

The distinction between credibility and reliability

As the finder of fact in this case, I am conscious of the difference between credibility and reliability. Credibility refers to the honesty or truthfulness of the witness. Reliability concerns the witness's ability to give an accurate account. Credibility and reliability are not the same things. A witness may be entirely honest or truthful, but inaccurate. In the present case, neither the State nor Mr Davidson took any issue with the honesty or truthfulness of any witness. However, as will be seen, issue was taken with the reliability of the opinions expressed in the expert psychiatric evidence.
The acceptance of a witness's testimony is not an all or nothing matter. I may accept some parts of a witness's testimony, but not others.

Witnesses whose statements were read into evidence, special witnesses and video‑link witnesses

For convenience and with the consent of Mr Davidson, a number of statements given to police by prosecution witnesses were read into evidence. The witnesses whose statement were read into evidence were:
•Kylie Jones
•Police officer Marissa Smolowitz
•Police officer Naomi Bass
•Police officer Joseph Lawley
•Police officer Neil Evans
•Police officer Nadia Poulsen
•Police officer Michael Chinn
The evidence of these witnesses was not contested by Mr Davidson, and I accept it.
Sharon Deierkauf, who was Mr Stokes' partner, and Ms Ugle, the alleged victim in count 1, were both declared special witnesses and gave their evidence from a remote room by CCTV. Daniel Watson, a former police officer, and Dr Michael Robertson, a toxicologist called by the defence, gave evidence via video‑link. The fact that a witness was declared a special witness or gave evidence via CCTV or video‑link are routine procedures of this court. No inference, adverse or otherwise, is drawn from the use of these procedures.

Multiple charges

The two charges that Mr Davidson faces arise predominantly out of closely‑connected events which occurred on 17 October 2019. Although count 2 is alleged to have occurred on 20 October 2019 at Perth, Mr Stokes' alleged murder arises out of acts committed by Mr Davidson on the evening of 17 October 2019 at 19A Forward Street, Mandurah, shortly after the alleged commission of count 1. Mr Davidson was charged with Mr Stokes' murder on 20 October 2019 at Perth because Mr Stokes died at Sir Charles Gairdner Hospital on 20 October 2019[5] as a consequence of injuries that he received at the hands of Mr Davidson.
[5] Exhibit 12.
While there is a degree of overlap in the evidence, each count must be considered individually. I must deliver a separate verdict on each count. The verdicts do not have to be the same. They may be different, depending upon the evidence relevant to each count.

Expert evidence

Expert evidence was adduced by both parties, most significantly from two forensic psychiatrists, Dr Adam Brett and Dr Victoria Pascu, who were called by the State and Mr Davidson, respectively. Expert toxicological evidence was also adduced from Dr David Joyce and Dr Robertson. By consent, three reports by forensic pathologist, Dr David Moss, were tendered by the State without the need for Dr Moss to give oral testimony.[6]
[6] ts 201, exhibit 11.
The expertise of these witnesses was not in dispute.
I am not bound to accept and act upon an expert witness's evidence, even if it is unchallenged. However, I cannot disregard unchallenged expert evidence capriciously. If there are no facts and no circumstances which, in my view, throw doubt on that evidence, I must accept it.
In the present case, there was significant disagreement between Dr Brett and Dr Pascu as to whether Mr Davidson was deprived of the capacity to know that he ought not do the acts which constituted each offence, and the extent to which Mr Davidson was intoxicated at the time of doing those acts. There was no dispute as to the findings of Dr Moss, and I accept them. There was little disagreement between Dr Joyce and Dr Robertson.
It is for me to resolve any conflict in the expert evidence.

Mr Davidson did not give evidence

Mr Davidson did not give evidence in the trial. It was his right not to do so, and his decision cannot be used in any way against him. It cannot be used to fill in any gaps that may exist in the State's case, nor can it be used as a makeweight in the State's case.

Inferences

I may draw inferences from the evidence. For example, each of the counts in the indictment requires proof by the State of an intention on the part of Mr Davidson. Inferential reasoning involves the drawing of a logical conclusion from proven facts. In drawing inferences, it is necessary to consider the relevant evidence as a whole and not to examine it in a piecemeal way.
An inference adverse to Mr Davidson cannot be drawn unless it is the only inference that is reasonably open on the evidence. If there is an innocent explanation that is reasonably open, then an inference of guilt cannot be drawn. Consistently with where the onus of proof lies, the State must exclude any possible reasonable inference consistent with innocence. For an inference to be reasonable it must rest upon something more than mere conjecture. The bare possibility of innocence does not prevent the drawing of an inference adverse to Mr Davidson if the inference is the only reasonable inference open upon a consideration of all of the facts proved by the evidence.

Elements of the alleged offences

I cannot find Mr Davidson guilty of count 1 unless I am satisfied that the State has proved each of the following elements of the offence beyond reasonable doubt:
(1)That he did an act.
(2)As a result of doing the act, the life, health or safety of Ms Ugle was, or was likely to be, endangered.
(3)That when he did the act, he did it with intent to harm.
Section 304(3) of the Code provides, relevantly to an offence contrary to s 304(2), that an intent to harm is an intent to:
(a)unlawfully cause bodily harm to any person; or
(b)unlawfully endanger the life, health or safety of any person.
In order to find Mr Davidson guilty of count 2, I must be satisfied that the State has proved beyond reasonable doubt each of the elements of the offence, being that:
(1)he killed Mr Stokes;
(2)the killing was unlawful; and
(3)he intended to cause the death of Mr Stokes, or intended to cause a bodily injury to him that was, objectively, of such a nature as to endanger, or be likely to endanger, Mr Stokes' life.
Section 270 of the Code provides that any person who causes the death of another person, either directly or indirectly, is deemed to have killed that person. Mr Davidson has admitted that he caused Mr Stokes' death. The first element of the offence of murder has been proved to the requisite standard by the State.
As to the second element of the offence of murder, s 268 of the Code provides that it is unlawful to kill any person unless the killing is authorised, justified or excused by law. Mr Davidson's killing of Mr Stokes will be excused, and therefore not unlawful, if he is not criminally responsible for killing Mr Stokes, having regard to s 27(1) of the Code.
As to the third element, the element of intention, it is well established that the issue of insanity, pursuant to s 27 of the Code, falls to be determined before the issue of intent. Thus, only if the question of insanity is answered adversely to the accused does the element of intention require consideration.[7]
[7] Ward v The Queen [2000] WASCA 413; (2000) 23 WAR 254 [25], [55] ‑ [57], [103].

Insanity - legal principles

Section 26 of the Code provides that every person is presumed to be of sound mind unless the contrary is proved.
Section 27 of the Code is as follows:
(1)A person is not criminally responsible for an act or omission on account of unsoundness of mind if at the time of doing the act or making the omission he is in such a state of mental impairment as to deprive him of capacity to understand what he is doing, or of capacity to control his actions, or of capacity to know that he ought not to do the act or make the omission.
(2)A person whose mind, at the time of his doing or omitting to do an act, is affected by delusions on some specific matter or matters, but who is not otherwise entitled to the benefit of subsection (1), is criminally responsible for the act or omission to the same extent as if the real state of things had been such as he was induced by the delusions to believe to exist.
In the present case, only subsection (1) is applicable. Senior counsel for Mr Davidson eschewed any reliance on subsection (2).
Section 1(1) of the Code defines 'mental impairment' as including mental illness. Mental illness is defined in s 1(1) to mean an underlying pathological infirmity of the mind, whether of short or long duration and whether permanent or temporary. As I have already mentioned, there is no dispute that at the time Mr Davidson did the acts said to constitute counts 1 and 2, he suffered from a mental illness and was mentally impaired.
Of the three capacities referred to in s 27(1) of the Code, the only one relevant to this case is the capacity to know that Mr Davidson ought not do, in the case of count 1, an act as a result of which the life, health or safety of Ms Ugle was, or was likely to be, endangered, and in the case of count 2, the acts which caused Mr Stokes' death. Mr Davidson does not allege that he was deprived of the other capacities referred to in s 27(1).
Mr Davidson has the burden of proving that he was not of sound mind at the time he did the acts alleged to constitute the offences on the balance of probabilities.[8]
[8] R v Porter [1933] HCA 1; (1933) 55 CLR 182.
The classic statement as to the meaning of the phrase 'capacity to know that he ought not to do the act or make the omission' was made by Dixon J in R v Porter, who said:[9]
We are dealing with one particular thing, the act of killing, the act of killing at a particular time a particular individual. We are not dealing with right or wrong in the abstract. The question is whether he was able to appreciate the wrongness of the particular act he was doing at the particular time. Could this man be said to know in this sense whether his act was wrong if through a disease or defect or disorder of the mind he could not think rationally of the reasons which to ordinary people make that act right or wrong? If through the disordered condition of the mind he could not reason about the matter with a moderate degree of sense and composure it may be said that he could not know that what he was doing was wrong. What is meant by 'wrong'? What is meant by wrong is wrong having regard to the everyday standards of reasonable people.
[9] Porter (189 - 190).

Dixon J went on to explain the meaning of 'incapacity' as:[10]
… not that he reasoned wrongly, or that being a responsible person he had queer or unsound ideas, but that he was quite incapable of taking into account the considerations which go to make right or wrong.
[10] Porter (190).
In Stapleton v The Queen,[11] it was held that what is required is that an accused knows right from wrong, good from evil, not legality from illegality. However, the High Court observed:[12]
The truth perhaps is that, from a practical point of view, it cannot often matter a great deal whether the capacity of the accused person is measured by his ability to understand the difference between right or wrong according to reasonable standards, or to understand what is punishable by law, because in serious things the two ideas are not easily separable. But in certain cases where the insane motives of the accused arise from complete incapacity to reason as to what is right or wrong … he may yet have at the back of his mind an awareness that the act he proposes to do is punishable by law.
[11] Stapleton v The Queen[1952] HCA 56; (1952) 86 CLR 358.
[12] Stapleton (375).
The real issue to be decided is whether Mr Davidson has established on the balance of probabilities that at the time of doing the acts the subject of each count, his mental impairment resulted in a complete incapacity (not merely a diminished capacity) to reason as to what is right or wrong according to ordinary standards. The term 'know' in s 27(1) of the Code means 'understand', 'appreciate' or 'comprehend'. As McLure P put it in Evans v The State of Western Australia:[13]
An incapacity to reason rationally as to what is right or wrong according to ordinary standards prevents a person from understanding that he (or she) ought not do the act. Knowledge (short of understanding) that to kill is punishable by law does not prevent such a finding. Nor is a finding of incapacity dependent upon proof of a positive belief in the rightness of the conduct. Whether an act is right or wrong is determined by reference to an objective standard. The question is whether the appellant had a complete incapacity to reason as to what was, by that objective standard, right or wrong.
[13] Evans v The State of Western Australia [2010] WASCA 34 [31].
I agree with the statement made recently by Derrick J in The State of Western Australia v Taylor:[14]
[T]he position can, in light of the above referred to authorities, be stated as follows: a person will be deprived of the capacity to know that they ought not to do the act or make the omission if they have a complete incapacity to understand, appreciate or comprehend that the act … is wrong according to ordinary standards (as distinct from unlawful).
[14] The State of Western Australia v Taylor[2021] WASC 470 [59].

Intoxication - applicable legal principles

Section 28 of the Code states:
(1)Section 27 applies to the case of a person whose mind is disordered by intoxication or stupefaction caused without intention on his part by drugs or intoxicating liquor, or by any other means.
(2)Section 27 does not apply to the case of a person who has intentionally caused himself to become intoxicated or stupefied, whether in order to afford excuse for the commission of an offence or not.
(3)When an intention to cause a specific result is an element of an offence, intoxication whether complete or partial, and whether intentional or unintentional, may be regarded for the purpose of ascertaining whether such an intention in fact existed.
Where there is a question about whether an accused intentionally caused themselves to become intoxicated, the onus is on the accused to prove, on the balance of probabilities, that they did not intentionally cause themselves to become intoxicated.[15]
[15] The State of Western Australia v Daly [2019] WASC 386 [37], [81].
Section 28 of the Code concerns the effect on criminal responsibility of a person's intoxication or stupefaction. In the present case, it is common ground that Mr Davidson had intentionally consumed methylamphetamine. I will, for convenience, refer to the effects of methylamphetamine on Mr Davidson as intoxication, rather than stupefaction. The terms are largely synonymous, and, for present purposes, stupefaction does not add anything of significance.
As to the meaning of the word 'intoxication' in s 28(1) and s 28(2), the State and Mr Davidson submitted that I should adopt and apply the meaning given to that word by Jenkins J in The State of Western Australia v Herbert.[16] In that case, her Honour said that the most appropriate definition of 'intoxication' is 'overpowering action or effect on the mind'. Dr Joyce and Dr Brett, in effect, regarded this definition as more demanding than they would apply. In my view, there is room for a construction of the word which is less demanding. However, as Jenkins J's definition was not challenged in this case, indeed it was accepted by the parties, I will apply it. Her Honour also stated in Herbert that the words 'become intoxicated' in s 28(2) refer to a person who has become intoxicated at the time of the commission of the relevant acts. Further, her Honour stated that the state of intoxication referred to in s 28(2) may be longer than the time the relevant accused subjectively experienced the effects of the drugs or liquor. She expressly agreed with the conclusion of the Queensland Court of Appeal in R v Clough (No 2),[17] that the ordinary meaning of 'intoxication' is wide enough to encompass more than comparatively short‑term elation or stimulation. These statements were recently adopted and applied by Derrick J in The State of Western Australia v Knock.[18]
[16] The State of Western Australia v Herbert [2017] WASC 101 [58] ‑ [59].
[17] R v Clough (No 2) [2010] QCA 120; (2011) Qd R 222.
[18] The State of Western Australia v Knock [2020] WASC 246 [56].
A question arose in the present case as to the interaction of s 27(1) and s 28(2) of the Code. This issue had been the subject of some controversy with different views being expressed by Jenkins J in Herbert and Derrick J in Knock. At the time closing submissions were made in this case, the Court of Appeal had not delivered judgment in Stefanski v The State of Western Australia.[19] On 31 January 2022, after I reserved judgment in this case, the judgment in Stefanski was delivered. Stefanski resolved the controversy I referred to. In fairness to the parties, I invited oral submissions as to the effect on the present case, if any, of Stefanski. On 8 February 2022, I heard brief oral submissions from the parties as to its effect.
[19] Stefanski v The State of Western Australia [2022] WASCA 5.
In Stefanski, issues of construction arose in respect of both s 28(1) and s 28(2). It is unnecessary to refer to the issue of construction with respect to s 28(1). This is because it has not been suggested that if Mr Davidson was intoxicated at the time of the acts the subject of the alleged offences, his intoxication was caused without intention on his part. However, the issue of construction with respect to s 28(2) of the Code is relevant to the present case.
Each of the judges in Stefanski (Buss P, Beech JA and myself) wrote separate reasons. However, each judge arrived at the same conclusion. Buss P expressed this conclusion, as follows:[20]
[20] Stefanski [152] - [154], [158].
So, by s 28(2), if an accused has intentionally caused himself or herself to become intoxicated or stupefied, the accused is not relieved of criminal responsibility if the intoxication or stupefaction deprives him or her of one or more of the capacities referred to in s 27(1). See Arnold [44].
However, s 28(2) does not preclude an accused, who has intentionally caused himself or herself to become intoxicated or stupefied, from relying upon s 27(1) if the accused is able to prove, on the balance of probabilities, that at the time of doing the act or making the omission:
(a)the accused suffered from a 'mental impairment', as defined in s 1(1), independently of and without regard to the accused's intoxication or stupefaction; and
(b)at the time of doing the relevant act or making the relevant omission, the accused was in such a state of 'mental impairment', as defined in s 1(1), as to deprive him or her of at least one of the capacities referred to in s 27(1), independently of and without regard to the accused's intoxication or stupefaction.
Section 28(2), read and construed having regard to s 27 and in the context of s 28(1), does not have the effect that s 27(1) does not apply, in any circumstances, to an accused who has intentionally caused himself or herself to become intoxicated or stupefied. There is no warrant for that conclusion in the text of s 28(2) when regard is had (as it must be) to the wider statutory context and the purposes of s 26, s 27 and s 28.
…
The answer to the Second Issue of Construction is that, in the case of an accused who intentionally caused himself or herself to become intoxicated, the accused may rely upon the excuse in s 27(1) if the accused can prove that it was a 'mental impairment' (as defined in s 1(1)), independently of and without regard to the intoxication, which caused the accused to be deprived of a relevant capacity (referred to in s 27(1)).

The facts of the offending

As senior counsel for Mr Davidson made clear in her closing address, there was no challenge to the evidence led by the State as to what occurred on 17 October 2019 and the events surrounding that day.[21] I am satisfied that the following matters of fact are proved.

Background

[21] ts 405 - 406.

Mr Davidson was born on 18 November 1973. Thus, as at 17 October 2019, he was 45 years of age.
In about 2000, Mr Davidson was diagnosed with bipolar affective disorder. In 2006, he was also diagnosed with schizoaffective disorder.
Between 2010 and 2019, Mr Davidson was admitted to hospital on eight occasions in connection with his mental health. In 2019, he was living in the community and was, for part of the year, under the care of the Peel Community Mental Health Service. The Service noted that Mr Davidson engaged poorly with it. The last occasion on which Mr Davidson was provided with a depot injection of his medication, paliperidome, was on 6 June 2019. On 24 July 2019, Mr Davidson presented at the Service in what was recorded to be an intoxicated state. On 1 August 2019, Mr Davidson was discharged from the Service. His last contact with the Service was an attendance on 24 September 2019. He did not receive any medication on this occasion.
In 2019, Mr Davidson was in an 'off and on' relationship with Ms Delle‑Grazie.[22] Both Mr Davidson and Ms Delle‑Grazie lived on the streets and used methylamphetamine and cannabis. In October 2019, they would, if they could, use methylamphetamine every day.[23] Mr Davidson's behaviour deteriorated after the cessation of his medication.[24] Mr Davidson's was, at times, physically violent towards Ms Delle‑Grazie, including choking her.[25]
[22] Ms Delle‑Grazie, ts 86.
[23] Ms Delle‑Grazie, ts 87.
[24] Ms Delle‑Grazie, ts 100 - 101.
[25] Ms Delle‑Grazie, ts 97, 101.
The deceased, Mr Stokes, lived with Ms Deierkauf in a house at 19B Forward Street, Mandurah (the house). They had been living together since about 2017.[26] Mr Davidson and Ms Delle‑Grazie moved into the house a week or two prior to 17 October 2019.[27] Prior to that, they had been living on the streets. Mr Davidson and Ms Delle‑Grazie occupied a bedroom in the house. The main bedroom was occupied by Mr Stokes and Ms Deierkauf.
[26] Ms Deierkauf, ts 44.
[27] Ms Delle‑Grazie, ts 87.
Mr Stokes, who was 43 years of age as at 17 October 2019, was a user of methylamphetamine. In the four days prior to 17 October 2019, Mr Stokes, Mr Davidson and Ms Delle‑Grazie used methylamphetamine.[28] On the first of these four days, all three of them used methylamphetamine. After that, only Mr Stokes and Mr Davidson used methylamphetamine. There is no evidence as to how much of the drug they consumed in the four‑day period leading up to 17 October 2019.
[28] Ms Delle‑Grazie, ts 88 - 89.
A rental inspection of the house was due to take place on the morning of 17 October 2019. There was some apprehension on the part of Mr Stokes, and perhaps Ms Deierkauf, about this.

The events of 17 October 2019

On 17 October 2019, Mr Davidson was agitated, somewhat angry and sleep‑deprived, having not slept for 'a couple of' days.[29]
[29] Ms Delle‑Grazie, ts 92.
Early that morning, Mr Davidson asked Ms Delle‑Grazie to inject him with methylamphetamine. She refused. This refusal led to an argument. She said that Mr Davidson 'sat there loaded'.[30] By 'loaded', she meant that he sat there with a syringe which contained methylamphetamine. She did not see Mr Davidson inject the contents of the syringe. While Ms Delle‑Grazie did not see Mr Davidson inject the methylamphetamine, I am satisfied that he did. I am satisfied of this fact because Mr Davidson had been using the drug for the previous few days and generally was using the drug whenever he could. It is highly unlikely that, having a syringe with methylamphetamine in it, he would not have injected it. I am unable to make any finding as to the quantity or purity of the methylamphetamine he injected.
[30] Ms Delle‑Grazie, ts 98 - 99.
Later in the morning of 17 October 2019, Mr Stokes and Ms Deierkauf requested both Mr Davidson and Ms Delle‑Grazie to leave the house for the rental inspection. This caused Mr Davidson and Ms Delle‑Grazie to have 'a couple of words'.[31] Eventually, they left the house. Ms Delle‑Grazie went to a shop. Mr Davidson went elsewhere.[32] Mr Davidson was in and out of the house throughout the day. On the occasions when he returned, he was in an agitated state.[33]
[31] Ms Delle‑Grazie, ts 92 - 93.
[32] Ms Delle‑Grazie, ts 93.
[33] Ms Delle‑Grazie, ts 95.
At some point in the day, Ms Ugle visited the house. At the time, Mr Stokes, Ms Deierkauf and Ms Delle‑Grazie, but not Mr Davidson, were there. She asked for, and obtained from Mr Stokes, a loan of $100 to buy drugs. Ms Ugle purchased one 'packet' of methylamphetamine and some cannabis with the money. When she returned to the house, she and Mr Stokes 'shot it [the methylamphetamine] up'.[34]
[34] Ms Ugle, ts 73.
At about 2.00 pm, Mr Davidson visited Lotteries House in Mandurah for no apparent purpose. As part of its case, and with the consent of Mr Davidson, the State tendered CCTV footage taken at Lotteries House of Mr Davidson.[35] The footage has no soundtrack. It shows Mr Davidson moving about the premises and outside them. Mr Davidson's behaviour displayed in the footage is abnormal. He moves and behaves without any evident purpose. At times, he makes strange gestures with his hands and makes unusual body movements. Mr Davidson rearranges a doormat, appears to explore a corridor, spends time looking through closed glass doors, goes into an outdoor garden area and squats for lengthy periods of time near this area on the path leading to the front doors of the building. At one point, he looks as if he is speaking to himself or some imaginary person.
[35] Exhibit 7.
Late in the afternoon of 17 October 2019, Mr Davidson visited Ms Bennell at her house in Mandurah. She had known Mr Davidson for about 30 years and saw him regularly, perhaps once a week. In her evidence, she referred to herself as Mr Davidson's 'black mum'.[36] While at her house, Mr Davidson started crying and said something to her about 'four blokes belting the piss out of him'.[37] She described Mr Davidson as 'very strange when he came there that day'. Mr Davidson was highly upset at the time he visited Ms Bennell.
[36] Ms Bennell, ts 105.
[37] Ms Bennell, ts 109.
At about 6.00 pm on 17 October 2019, Mr Davidson returned to the house. Having regard to the evidence of Ms Deierkauf, Ms Ugle and Ms Delle‑Grazie, who were present, he was in an angry and loud mood.
At some point, Mr Davidson, still in an angry mood, entered the bedroom he occupied with Ms Delle‑Grazie.[38] He shouted at her.[39] Ms Delle‑Grazie asked Mr Stokes to request Mr Davidson to leave the house.[40] Mr Stokes did so. The two men yelled at each other.[41] Mr Davidson asked where Ms Delle‑Grazie was. By this time, Ms Delle‑Grazie was hiding in the toilet.
[38] Ms Delle‑Grazie, ts 96.
[39] Ms Ugle, ts 76.
[40] Ms Delle‑Grazie, ts 96.
[41] Ms Delle‑Grazie, ts 96.
The precise events leading up to the alleged commission of counts 1 and 2 are not completely clear. Based on the evidence of Ms Deierkauf and Ms Ugle, I am satisfied that Mr Davidson struck Mr Stokes with a tennis racquet in the hallway of the house near the kitchen.[42] Ms Ugle then ran into the main bedroom. Mr Davidson entered this bedroom and struck Ms Ugle with the tennis racquet, knocking her to the floor. Mr Davidson then kicked her. I am unable to find precisely the number of times Mr Davidson hit and kicked Ms Ugle, but I am satisfied that he administered multiple blows to Ms Ugle. Ms Ugle described Mr Davidson as 'kicking the shit' out of her and 'knocking the wind' out of her.[43] I find that Mr Davidson struck Ms Ugle with some force.
[42] Ms Deierkauf, ts 63; Ms Ugle, ts 77.
[43] Ms Ugle, ts 79.
As Mr Davidson assaulted Ms Ugle, Mr Stokes entered the room. He stood between Mr Davidson and Ms Ugle and told her to run. Ms Ugle crawled between Mr Stokes' legs and ran out of the room, through the back door and over the fence.[44] She managed to get someone to ring the police.[45] By this time, Ms Deierkauf and Ms Delle‑Grazie had also left the house.
[44] Ms Ugle, ts 79.
[45] Ms Ugle, ts 80.
Ms Ugle returned to the house. When Ms Ugle entered the house, Mr Davidson was on top of Mr Stokes, choking him[46] and pounding his head on the floor.[47] In an attempt to get Mr Davidson off Mr Stokes, Ms Ugle picked up a big vase and smashed it against the back of Mr Davidson's head. This stunned Mr Davidson.[48] Ms Ugle then ran out of the house again.[49]
[46] Ms Ugle, ts 80.
[47] Ms Ugle, ts 80 - 81.
[48] Ms Ugle, ts 80.
[49] Ms Ugle, ts 81.
Ms Kylie Jones, whose witness statement was read to the court,[50] had an uninterrupted view of the front of the house from a distance of about 40 m. She saw and heard what happened next.
[50] Statement of Kylie Marie Jones, ts 113.
She saw that Mr Davidson was on top of Mr Stokes, and heard Mr Davidson shout, 'I'm going to kill you, you black cunt'. She also saw Mr Davidson repeatedly strike Mr Stokes with a hammerlike fist motion. Mr Stokes was screaming for help.[51]
[51] Statement of Kylie Marie Jones, ts 112.
Eventually, Mr Stokes fell silent. Mr Davidson's attack continued. Mr Davidson rained blows on Mr Stokes who, by this time, was lying face‑down on the floor in the passageway close to the front door. He was motionless. Mr Davidson then leant in and placed his arm around Mr Stokes' neck in a chokehold.[52]
[52] Statement of Kylie Marie Jones, ts 112 - 113.
Ms Jones called the police. Mr Davidson remained on top of Mr Stokes and kept up the attack upon him until the police arrived.[53]
[53] Statement of Kylie Marie Jones, ts 113.
The first police officers on the scene were Constable Daniel Watson and Constable Michael Oliver. They arrived at the house just after 9.00 pm. They went to the front door of the house. The front door was open, but the flyscreen was locked. Mr Davidson was on top of Mr Stokes on the floor near the front door. Mr Davidson did not respond when Constable Watson asked, 'What's going on?'[54]
[54] Constable Watson, ts 126.
Constable Watson entered the house through the rear door. He went through the house towards the front door. He told Mr Davidson to move off the person below him. Mr Davidson did not distinctly respond. There was 'just a lot of mumbling'.[55] Constable Watson then attempted to sit Mr Davidson up, after which he opened the front door to allow other police officers to enter the house.[56]
[55] Constable Watson, ts 125 - 126.
[56] Constable Watson, ts 126 - 127.

Mr Davidson was observed to be 'extremely sweaty' and there was blood on his head.[57]
[57] Constable Watson, ts 127.
Constable Watson helped Mr Davidson to his feet and took him to the kitchen, where he sat on a chair. There, he was handcuffed.[58] When asked by Constable Watson, 'Have you got any injuries?' and 'What's going on?', Mr Davidson gave no clear response.[59]
[58] Constable Watson, ts 127.
[59] Constable Watson, ts 127.
An ambulance officer, Ashley Low, examined Mr Davidson while he was seated in the kitchen. When Mr Low asked Mr Davidson if he had any injuries, he did not respond, but he turned his head to the right to expose a small laceration and swelling behind his left ear. There were no other injuries observed.[60]
[60] Ashley Low, ts 133 - 134.
Constable Watson stayed with Mr Davidson in the kitchen for about 10 minutes.[61] During this time, Mr Davidson was motionless and mumbling. Towards the end of this 10‑minute period, he became quite angry and was shouting.[62]
[61] Constable Watson, ts 128.
[62] Constable Watson, ts 128.
Other police officers soon arrived at the scene. Constable Oliver and other police officers began performing CPR on Mr Stokes, who was eventually moved out of the house and onto the front yard. After a period of time, Mr Stokes was taken by ambulance to the Peel Health Campus.[63]
[63] Constable Farnworth, ts 139.
At around 9.50 pm, Mr Davidson was placed in the secure pod of a police vehicle.[64] In the process of being placed into the pod, Mr Davidson was yelling out words and rambling indistinctly.[65] By this time, Mr Davidson was wearing a police‑issue forensic bodysuit and had his hands wrapped in paper bags.[66] After he was placed in the pod of the police vehicle, Mr Davidson tried to take the paper bags off his hands with his teeth.[67] Before he was taken from the scene, Mr Davidson was constantly shouting. At one point, he said, 'Suck blood you fucking cunt. Fuck you, you fucking nigger', and something about 'smashing teeth in' and 'Meekatharra'.[68]
[64] Statement of Marissa Smolowitz, ts 141.
[65] Constable Oliver, ts 131.
[66] Statement of Marissa Smolowitz, 141.
[67] Statement of Naomi Bass, ts 146 - 147.
[68] Statement of Marissa Smolowitz, ts 141 - 142.
At about 10.34 pm on 17 October 2019, Senior Constable Bass and Senior Constable Paul Longden drove Mr Davidson in the police pod to the Rockingham Hospital.[69]
[69] Statement of Naomi Bass, ts 147.
During the journey from the house to the Rockingham Hospital, Mr Davidson was rambling, shouting aggressively, swearing and smacking his lips. He was incoherent.[70]
[70] Senior Constable Longden, ts 154 - 155.
At about 10.57 pm on 17 October 2019, the police vehicle carrying Mr Davidson arrived at Rockingham Hospital.[71] Senior Constable Bass went into the hospital to organise a room for Mr Davidson, while Senior Constable Longden remained in the police vehicle with him.[72]
[71] Statement of Naomi Bass, ts 147.
[72] Senior Constable Longden, ts 155.
For the first 15 to 20 minutes of the period in which Mr Davidson was held in the pod waiting for a room to become available in the hospital, he continued to shout incoherently and swear. Eventually, he fell silent and appeared to be sleeping.[73]
[73] Senior Constable Longden, ts 156.
It took until about 11.40 pm for Mr Davidson to be escorted into the hospital and be placed into a room called the 'in‑hold room'.[74]
[74] Statement of Naomi Bass, ts 147.
At about 11.45 pm on 17 October 2019, Mr Davidson's clothing was seized and he was given a new blue forensic bodysuit to wear. Mr Davidson asked if he had any rights. Senior Constable Bass observed that Mr Davidson was 'conversing better' and administered a caution and informed him of his rights under s 137 and s 138 of the Criminal Investigation Act 2006 (WA). Mr Davidson did not invoke any of these rights.[75]
[75] Statement of Naomi Bass, ts 147. Mr Davidson had been cautioned and advised of his rights under s 137 and s 138 of the Criminal Investigation Act2006 (WA) at 9.14 pm by Detective First Class Calley. Mr Davidson made no coherent response to the caution or the advice as to his rights.
Mr Davidson remained at the hospital for some hours. He slept most of the time and was quite calm.[76]

The events of 18 October 2019

[76] Senior Constable Longden, ts 157.

At about 4.00 am on 18 October 2019, Mr Davidson was awoken by a doctor at the Rockingham Hospital.[77] Detective Baker advised Mr Davidson that he was under arrest on suspicion of attempted murder, and provided Mr Davidson with his rights in accordance with s 137 and s 138 of the Criminal Investigation Act. He was also cautioned. Mr Davidson did not apparently understand the caution, and a short time later began to cry.
[77] Detective Baker, ts 175.
Mr Davidson was then taken to the Mandurah police station, arriving there at about 4.30 ‑ 4.45 am.[78]
[78] Detective Baker, ts 176.
CCTV footage was taken of Mr Davidson while at the Rockingham Hospital.[79] It is unnecessary to describe what is shown in that footage.
[79] Exhibit 8.
Shortly after Mr Davidson's arrival at the Mandurah police station, Detective Bray asked Mr Davidson, and Mr Davidson agreed, to be interviewed by police.[80] At about 6.35 am, Detective Bray and Detective Garnaut interviewed Mr Davidson. The interview was video‑recorded.[81] Shortly after it commenced, the interview was terminated by Detectives Bray and Garnaut because of Mr Davidson's behaviour and, in particular, because Mr Davidson was unable to explain or demonstrate his understanding of the caution.[82] Mr Davidson's behaviour in the interview was agitated and angry, often swearing and shouting. Much of what he said was incoherent. At one point, he used his fingers to shape a handgun and pointed it to the camera in the interview room.[83]
[80] Detective Bray, ts 193 - 194.
[81] Exhibit 10.1.
[82] Detective Bray, ts 196 - 197.
[83] This is borne out by a transcript of the interview prepared by Mr Davidson's lawyers which was, with the consent of the State, tendered as an aid to understanding what Mr Davidson said to the police: see ts 362 ‑ 363, exhibit 10.2.
After the interview was terminated, Mr Davidson was taken to the Perth Watch House, where he arrived shortly before 9.00 am.[84]
[84] Statement of Michael Phillip Chinn, ts 180 - 181.
Mr Davidson appeared in the Magistrates Court on 18 October 2019 and was referred to the Frankland Centre on a hospital order. A discharge summary, dated 29 October 2019, which was tendered in evidence, noted that Mr Davidson presented in court 'as labile, distracted, thought disordered and nonsensical'.[85] He reported no recollection of the alleged offending, nor an understanding of the charges before the court, before proceeding to punch his head repeatedly while citing various names from the Bible and making bizarre statements, such as 'Jesus is not his father'.
[85] Discharge summary, exhibit 18, page 1.
The discharge summary records:[86]
On admission, Mr Davidson presented as dishevelled and agitated. He was irritable and labile, yelling during the interview in thought disordered and irrelevant fashion. He appeared to be responding to internal stimuli and was described as insightless.
[86] Discharge summary, exhibit 18, page 2.
Initially, Mr Davidson was sedated. On 22 October 2019, he was restarted on his Paliperidone injections. It was noted that Mr Davidson's psychotic symptoms and level of thought disorder improved rapidly, such that by the afternoon of 22 October 2019, he had gained insight into the alleged charges. He was noted to be highly distressed at hearing the news that Mr Stokes had died and that the charge laid against him had been upgraded to murder.[87]
[87] Discharge summary, exhibit 18, page 2.
On 28 October 2019, Mr Davidson was discharged from the Frankland Centre and returned to custody.

The post-mortem

As I have mentioned, Mr Stokes died in hospital on 20 October 2019.
On 23 October 2019, Dr David Moss, a forensic pathologist, conducted a post‑mortem examination on Mr Stokes. This examination revealed extensive skin and soft tissue bruising. Dr Moss noted 17 separate injuries to Mr Stokes' head and neck regions, which resulted in a cardiac arrest. Although resuscitation was successful, hypoxic ischaemic encephalopathy and bronchopneumonia developed, which, despite 'maximal hospital care', led to Mr Stokes' death.[88]
[88] Exhibit 11.
Dr Moss was aware of a toxicology report, dated 27 November 2019, which revealed the presence of methylamphetamine and its metabolite, amphetamine, in an ante‑mortem blood sample taken from Mr Stokes on 17 October 2019.[89]
[89] Exhibit 13.
In Dr Moss' initial report to the coroner, dated 28 October 2019, he was unable to determine the cause of death, but in a supplementary report, dated 8 December 2020, Dr Moss expressed his opinion that the cause of death was 'hypoxic ischaemic encephalopathy and bronchopneumonia, complicating head and neck injury in a man with recent methylamphetamine use'.[90]
[90] Exhibit 11.
I find that Mr Davidson inflicted multiple injuries upon Mr Stokes, which, having regard to Dr Moss' findings, led to cardiac arrest. Although Mr Stokes was able to be resuscitated, the cardiac arrest led to the conditions from which he died. As I have already mentioned, Mr Davidson admits that his acts caused Mr Stokes' death, and I so find.

The toxicological evidence

A sample of blood was taken from Mr Davidson at 2.00 am on 18 October 2019. The ChemCentre certificate of analysis, dated 11 December 2019, with respect to this sample is set out on the following page:[91]

[91] Exhibit 14.

It will immediately be observed that methylamphetamine, amphetamine and tetrahydrocannabinol were detected in Mr Davidson's blood.
The State and Mr Davidson each led expert evidence as to the significance of the presence of methylamphetamine, amphetamine and tetrahydrocannabinol in Mr Davidson's blood. The State adduced evidence from Dr David Joyce, a physician and clinical pharmacologist and toxicologist. The defence adduced evidence from Dr Michael Robertson, a consulting pharmacologist and forensic toxicologist and chemist. The qualifications and expertise of these witnesses were unchallenged, and I accept that each had the knowledge and experience to give evidence as to the significance of the presence of the illicit drugs detected in Mr Davidson's blood sample. I will deal first with the evidence of Dr Joyce, and then the evidence of Dr Robertson.

Report of Dr Joyce dated 17 May 2021

Dr Joyce's report of 17 May 2021 was tendered in evidence as exhibit 15.
The purpose of the report was stated to be:
This report is made in response to instructions from the Office of the Director of Public Prosecutions for WA to Professor David Joyce to provide advice on the potential effects of drugs on Mr Davidson at the time of the alleged offences, taking into account the concentrations of drugs present in a blood specimen collected later.
In order for Dr Joyce to provide the advice sought, he was provided with: witness statements of those persons who observed Mr Davidson's actions, appearances and behaviour at the relevant times; descriptions of Mr Davidson's illicit drug use; the ChemCentre report, dated 11 December 2019; a timeline of relevant events between 13 July 2019 and Mr Davidson's interview with police on 18 October 2019; information regarding Mr Davidson's psychiatric history, including the opinion of Dr Pascu, dated 26 June 2020; the video footage of Mr Davidson at Lotteries House, Rockingham Hospital and the Mandurah police station, including a video recording of the record of interview which took place between Detective Bray and Mr Davidson commencing at 6.35 am on 18 October 2019; and Dr Robertson's report, dated 27 October 2020.
As to the results of the analysis of Mr Davidson's blood, set out at [105] above, Dr Joyce reported that:
(a)Alcohol was not detected. As the blood specimen was collected about five and a half hours after the alleged attack, any alcohol that may have been present in Mr Davidson's blood at the relevant time could have disappeared. Dr Joyce assumed that alcohol was 'unimportant in making this report'.
(b)The negative screening procedures for other common basic drugs gives 'very good reassurance that other intoxicants were not involved'.
(c)Diazepam is a benzodiazepine sedative drug, best known by the trade name 'Valium'. Desmethyldiazepam is a metabolite of diazepam. Dr Joyce described the concentration of both drugs as 'low' and said that the concentrations would have been similarly low at the time of the commission of the alleged offences. They had no material effect on Mr Davidson's mind at any relevant time.
(d)Methylamphetamine and tetrahydrocannabinol were the drugs of importance in this case. Amphetamine is made during methylamphetamine's metabolism in the body. This explains its presence in the blood analysis in low concentrations.
Dr Joyce noted the psychiatric diagnoses of Dr Griffiths at the Frankland Centre and Dr Pascu. Each diagnosed Mr Davidson as suffering from schizoaffective disorder, bipolar type. Each noted Mr Davidson's prior abuse of methylamphetamine and cannabis.
Dr Joyce said that the roles of cannabis and, especially, methylamphetamine, in pushing psychiatric disorders out of control is well recognised.
With respect to cannabis, sedation is one of the characteristics of intoxication. Violence is unusual. In Dr Joyce's opinion, the concentration of cannabis in Mr Davidson's blood specimen was low. Concentrations under 1 µg/L can be detected in blood for even a day after a single use of an intoxicating, smoked, dose. The detection period can be longer for a regular user. The evidence did not suggest that Mr Davidson was intoxicated with cannabis at the time the offences were allegedly committed.
With respect to methylamphetamine, Dr Joyce regarded it as an 'uncontroversial' proposition that habitual methylamphetamine use worsened the clinical severity of Mr Davidson's psychiatric illness. He considered whether Mr Davidson was also in a state of methylamphetamine intoxication, and whether this intoxication was necessary for his psychiatric illness to manifest in lethal violence. Dr Joyce observed that, broadly speaking, there were two states of methylamphetamine intoxication that were characterised by a propensity to extreme violence. The first of these was 'amphetamine‑induced delusional psychosis'. Dr Joyce considered that this was not a relevant consideration in Mr Davidson's case because a sine qua non of this diagnosis is the absence of pre‑existing psychiatric disorders that could explain the psychosis. The second state which can give rise to extreme violence is 'acute intoxication'. This is a state that comes on shortly after the drug is used, and typically persists for around 6 to 12 hours. Violence carried out by an otherwise psychiatrically normal person during acute intoxication is a result of the state of intoxication that the person has induced. However, in a person who does have a psychiatric disorder, like Mr Davidson, it may be very difficult to judge whether the acute intoxication had a necessary role in transforming the psychiatric state from safety to violence.
Dr Joyce observed that there were three broad areas of evidence to consider in deciding whether a person is in a state of acute intoxication, or not. First, are the appearances, behaviour and thought processes consistent with a state of acute intoxication? Second, has a dose of methylamphetamine been taken recently (within the last 6 to 12 hours)? Third, is the blood concentration of methylamphetamine consistent with acute intoxication?
In answer to the first question, Dr Joyce described how an acutely intoxicated person might appear, behave and think. High doses of amphetamines may produce trembling, restlessness, irritability, impairment of coordination and motor control, and impairment of attention and concentration. Risk‑taking behaviour, recklessness, aggression and violence are common consequences of intoxication with amphetamines. Personality changes may occur, with suspiciousness and paranoia being particularly characteristic. Methylamphetamine, by virtue of its ability to create impulsiveness, will limit an individual's powers of self‑restraint. Simultaneously, its ability to engender agitation and a mood of aggression and suspicion will make it more likely that the user will be drawn into violence. The person may be unable to effectively check the impulsivity, anger and aggression that the drug brings. While a person in his normal mind would be likely to withdraw from attack after the impulse subsides, the stimulant user may experience a rage, where the impulse to attack and the ferocity of the attack do not readily subside. The emergence of a paranoid psychosis during acute methylamphetamine intoxication combines a paranoid justification for violence with the drive and capacity for violence. As such, it is a particularly dangerous state.
Dr Joyce observed that, based on the material that had been provided to him, Mr Davidson appeared to have displayed the anger and extreme violence that can be part of acute methylamphetamine intoxication. Dr Joyce noted that Mr Davidson appeared angry throughout 17 October 2019. The injuries revealed in the post‑mortem examination, the witness statements of Ms Jones, Ms Deierkauf and Ms Ugle and the fact that Mr Davidson did not seem to have disengaged from his attack on Mr Stokes until the police intervened were consistent with persisting intoxication. Dr Joyce referred to the CCTV vision of Mr Davidson at Lotteries House. He thought that the behaviour exhibited by Mr Davidson was 'sufficiently explained by his background psychiatric illness without requiring a second diagnosis of acute methylamphetamine intoxication'. Dr Joyce said that the CCTV vision of Mr Davidson at Rockingham Hospital showed attributes that were 'suspicious' of methylamphetamine intoxication, but had 'little specificity for it'. Mr Davidson's appearance during the video interview with police officers, commencing at about 6.35 am on 18 October 2019, raised suspicion of methylamphetamine intoxication, but did not prove it, given the background of Mr Davidson's mental impairment.
In respect of the second area of evidence considered by Dr Joyce, whether a dose of methylamphetamine had been taken recently, he observed that there was no reliable information on when Mr Davidson had his last dose of methylamphetamine.
As to the third area of evidence, whether the blood concentration of methylamphetamine was consistent with intoxication, Dr Joyce said that different amounts of methylamphetamine are needed to produce acute intoxication in different people, largely determined by how habituated a person was in taking the drug. Habitual users become tolerant and need more of the drug to become acutely intoxicated. While the evidence of Dr Pascu pointed to a habitual pattern of methylamphetamine use by Mr Davidson, there was no quantitative evidence of his use.
Dr Joyce said that methylamphetamine has a half‑life of between 8 and 18 hours. Mr Davidson's blood concentration of 0.03 mg/L meant that the concentration at the time of the offences was around 0.045 mg/L. This concentration was not particularly suggestive of acute intoxication. Dr Joyce said that his experience of methylamphetamine concentrations in people without background psychiatric illness who have committed violent crimes during acute intoxication is limited, but such people had concentrations of methylamphetamine which were 'a lot higher' than in Mr Davidson's case.
Dr Joyce concluded that the evidence did not 'point convincingly to a state of acute methylamphetamine intoxication when Mr Davidson carried out the attacks'. He added that Mr Davidson 'was probably not intoxicated with cannabis either'. However, he said that a decision that acute intoxication with methylamphetamine or cannabis was probably absent is not the same as saying they did not have a role in causing or facilitating Mr Davidson's psychiatric state.

The final part of Dr Joyce's report was taken up with answers to questions which had been posed to him. It is unnecessary to repeat each of the questions that were posed and the answers that were given. One of the questions posed was, 'Whether the accused was significantly affected or intoxicated by one or more of the drugs detected in his blood'.
Dr Joyce answered:
Mr Davidson was affected, in the sense that the drugs contributed to his psychiatric illness becoming uncontrolled. The evidence that he was in a state of acute intoxication, though, is limited. Low concentrations of methylamphetamine, however, are now turning up regularly in the blood of people with psychiatric illness, where violence is taken to be a manifestation of the illness. Therefore, there has to remain a suspicion that the methylamphetamine is a reason why the illness takes a violent form.
In answer to a series of questions, one of which was 'whether mental illness may affect how an individual is affected by drugs', Dr Joyce relevantly said:
The effects of methylamphetamine on mental illness are discussed above. In summary, methylamphetamine use will precipitate relapse in many psychiatric illnesses. Active psychiatric illness and the psychiatric effects of intoxication can co‑exist. Experience supports the view that recent methylamphetamine use, even at a level insufficient to overtly intoxicate, may flavour the symptomology of relapse towards violence. However, there is no published research or organised body of experience that tells us how to be sure that methylamphetamine is, or is not, the reason that the psychiatric illness is manifesting in violence.
Dr Joyce was asked to comment about Dr Robertson's conclusion in his report to the effect that all of the drugs present in Mr Davidson's blood samples were of low concentrations and that none of them, either alone or in combination, would be expected to result in serious adverse effects or 'intoxication' at the concentrations present. Dr Joyce agreed that the concentrations of tetrahydrocannabinol, diazepam and desmethyldiazepam were low. He confirmed that Mr Davidson would be unlikely to show acute methylamphetamine intoxication at 0.03 mg/L. Dr Joyce said that he would not accept that methylamphetamine did not contribute to the deterioration in Mr Davidson's psychiatric disorder if that was counter to the opinions of the two forensic psychiatrists. He thought that Dr Robertson's statement would be more complete if it was qualified by the observation that low concentrations of methylamphetamine are frequently encountered when relapsed psychiatric illness takes violent form.

Evidence of Dr Joyce

In his examination‑in‑chief, Dr Joyce referred to a report he wrote in respect of Mr Stokes and gave some brief evidence in respect of it. At the time of being asked to write his opinion, Dr Joyce was given the ChemCentre final report relating to Mr Stokes, which was tendered in evidence as exhibit 13. A blood sample taken from Mr Stokes shortly after his admission to hospital and prior to his death revealed the presence of methylamphetamine, amphetamines and tetrahydrocannabinol.[92] The level of methylamphetamine, 0.89 mg/L, was described by Dr Joyce as 'high'.[93] At this level, while Dr Joyce was unable to say exactly how it might have affected Mr Stokes, he said everybody would be affected by that level of methylamphetamine in their system.[94] Dr Joyce expressed the opinion that methylamphetamine intoxication was very unlikely to be a cause of Mr Stokes' death.[95]
[92] ts 206.
[93] ts 207.
[94] ts 207.
[95] ts 208.
Dr Joyce's attention was then turned to his report in respect of Mr Davidson, dated 17 May 2021,[96] and, in particular, the role that illicit drugs may have had on Mr Davidson's offending behaviour on 17 October 2019.
[96] Exhibit 15.
Dr Joyce said that there was no uniformly accepted definition in pharmacology or toxicology of the term 'intoxication' and that when he used the word 'intoxication' he did so 'to cover any adverse effect of methylamphetamine … on the person'.[97]
[97] ts 218 - 219.
Based on his understanding of the nature of Mr Davidson's attack upon Mr Stokes, Dr Joyce testified that, having regard to the circumstances as he understood them, Mr Davidson's behaviour appeared 'very similar to a number of other serious and lethal methylamphetamine‑induced attacks that have come in front of me in the severity of its nature and its duration'.[98] However, given that, in Mr Davidson's case, there may have been 'a psychiatric drive to undertake the attack', Dr Joyce said it was not within his expertise to comment on whether the attack was attributable to methylamphetamine.[99] He continued:[100]
Now, having been told by a competent and respected forensic psychiatrist that there - or two competent and respected forensic psychiatrists that there are background psychiatric disorders that - that may have turned Mr Davidson's mind to a state where he believed that the attack was justified there I would then stand back from - from making any - anything more than - than a proposal of amphetamine causation.
[98] ts 221.
[99] ts 221.
[100] ts 221.
Dr Joyce observed that Mr Davidson's attack on Mr Stokes looked like a methylamphetamine‑driven attack, but the level of methylamphetamine would be 'at the lowest concentration' that he had seen for such an attack.[101]
[101] ts 222.
When asked by the prosecutor whether it is possible that, for a person with a psychiatric illness, even low levels of methylamphetamine might have an adverse effect upon their behaviour, Dr Joyce said:[102]
I have to limit my response here to - to personal experience, be - because proper answers to that question haven't appeared in the literature. My own experience would leave me to suspect that the manifestations of psychiatric illness may be flavoured by the presence of methylamphetamine there, toward - towards violent manifestation. Now, the - the reason for saying that is because of the number of cases that come before me where there is a psychiatric illness and there is some methylamphetamine, and that - there has been violence. A - an epidemiologist would - would look at that evidence base and say that - that it is highly selected there. That I'm only seeing these instances, because they were referred to me and that maybe they are not representative of the broader experience there. So that - that's - that - that's as far as I can say on it. It's - it's my own suspicion that the flavour of psychiatric illness is influenced by the - the presence of methylamphetamine towards violent manifestation. But it's no more than a personal suspicion.
[102] ts 223.
In cross‑examination, Dr Joyce accepted that some of the behaviours he described as resulting from the effects of methylamphetamine use could also be signs of mental illness, and that it is not easy to differentiate between the two when they are both present in some form.[103] Further, Dr Joyce agreed that in a person such as Mr Davidson with schizoaffective disorder, it is difficult to judge whether acute intoxication had a necessary role in transforming the psychiatric state from safety to violence.[104] Moreover, Dr Joyce accepted that the level of methylamphetamine detected in Mr Davidson's blood was not indicative of acute intoxication.[105]
[103] ts 229 - 230.
[104] ts 230.
[105] ts 231.
I asked Dr Joyce about Mr Davidson's behaviour in his interview with police at about 6.30 am on 18 October 2019. He said that he was inclined to view Mr Davidson's behaviour in the interview as having been caused more by his mental illness than by methylamphetamine because the effects of the most recent dose would have largely subsided by that time.[106]
[106] ts 233.
Dr Joyce accepted that he was not able to draw any conclusion about Mr Davidson's behaviour, other than that he had a suspicion that it was influenced by his methylamphetamine use.[107]
[107] ts 235.
I also asked Dr Joyce about the definition he gave in his evidence of 'intoxication'. I informed him that a definition which the courts have used is 'subject to the overpowering action or effect of the drug'. I asked him if that was a different definition to the one that he had used, or whether it was the same. Dr Joyce responded that the definition I had described was 'not as accommodating' as the definition he had used.[108] Dr Joyce said that he would not have confidence in saying that Mr Davidson was overpowered by drugs at the time of the events which constituted the alleged offences.[109] Dr Joyce then made the general observation that people with psychiatric illness display more violent manifestations of that illness if methylamphetamine is present. However, he qualified this statement by stating that it came from his own experience and that it had not been broadly enough accepted in the literature for him to be sure if it was pervasive.[110]

Report of Dr Robertson

[108] ts 237.

[109] ts 237 - 238.

[110] ts 238.

Dr Robertson's report is dated 27 October 2020, and was admitted into evidence as exhibit 17.
Dr Robertson is a chemist, pharmacologist and forensic toxicologist. He is not a medical doctor. He was briefed on behalf of Mr Davidson to provide comment 'on whether Mr Davidson was significantly affected or "intoxicated" by one or more of the drugs detected in his blood'.
Dr Robertson was provided with material, including a statement of material facts, the ChemCentre report, dated 11 December 2019 (see [105] above), Dr Pascu's psychiatric report, a psychiatric report from Graylands Hospital, dated 23 October 2019, and 'various medical records'.
As to the level of methylamphetamine detected in Mr Davidson's blood at about 2.00 am on 18 October 2019, being 0.03 mg/L, Dr Robertson reported:
(e)Whilst it is not known when Mr Davidson last used methylamphetamine, it is not likely that the blood concentration of methylamphetamine was materially different at the time of the alleged offence (approximately 5.3 decimal hours earlier). However it is likely to have been slightly higher.
(f)Following the recreational use of methylamphetamine, blood concentrations typically exceed 0.1 mg/L. As such a blood concentration of 0.03 mg/L would be regarded as low and consistent with concentrations associated with 'therapeutic' use when methylamphetamine was explored for its clinical benefits.
(g)It is possible that a low amount of the drug was administered by Mr Davidson in the hour or hours prior to the offence, or that the amount in the blood represented some residual amount of drug that was administered a day or more previously.
(h)At a blood concentration of 0.03 mg/L or slightly higher, significant methylamphetamine‑related adverse effects or 'intoxication' is not likely.
As to the level of tetrahydrocannabinol being less than one 1 µg/L, Dr Robertson wrote:
(f)In frequent users of cannabis, detectable amounts of [tetrahydrocannabinol] in blood may persist for many days after last use and remain present at concentrations of approximately 0.05 g/L or more for a day or more after last use.
(g)As such with respect to cannabis, it can only be said that the results were that cannabis had been used by Mr Davidson at some stage prior to the collection of his blood.
(h)In the absence of knowing the time of the last use, it cannot be concluded that Mr Davidson was materially affected by cannabis at the time of the alleged assault and indeed there is no evidence that cannabis caused or contributed to any drug‑related adverse effects.
Dr Robertson expressed the view that the presence of diazepam would not have had any material effect on Mr Davidson at the time of the alleged offence.
Dr Robertson concluded his report, as follows:
In conclusion, all of methylamphetamine, [tetrahydrocannabinol], diazepam and desmethyldiazepam were present in the blood of Mr Davidson at low concentrations. None of these drugs, either alone or in combination, would be expected to result in serious adverse effects or 'intoxication' at the concentrations present.

Evidence of Dr Robertson

In examination‑in‑chief, Dr Robertson expressed his understanding of the meaning of 'intoxication', in these terms:[111]
Well, I'm using the term that is - it - it distorts a person's behaviour, cognitive abilities those sorts of things. So quite - that - that would be that sort of more profound intoxication. Under the influence or the effects of the drugs on someone might be those more therapeutic‑type effects that I've just described. That wouldn't necessarily be intoxication in this, as far as human performance‑type intoxication. And I use that distinctly from something like driving under the influence of a drug where lower levels might intoxicate someone for a - from a driving perspective. But I'm looking at intoxication as the drugs modifying, manipulating someone's behaviour or thought processes. There would be the case in this - in this situation.
[111] ts 244.
In examination‑in‑chief, Dr Robertson, in substance, confirmed the opinion he expressed in his report, that the levels of diazepam and desmethyldiazepam found in Mr Davidson's blood almost certainly would not cause any pharmacological effect, let alone any form of intoxication, either alone or in combination with any of the other drugs present at the time of the commission of the offences.[112]
[112] ts 243 - 244.
As to tetrahydrocannabinol, Dr Robertson noted that the level of tetrahydrocannabinol reported by the ChemCentre was below their limit of quantification.[113] Dr Robertson said that it was very difficult, 'without a solid history', to determine when the drug was last used.[114] In these circumstances, Dr Robertson said that it was very difficult to conclude too much about the significance of the level of tetrahydrocannabinol found in Mr Davidson's blood. He said that if there were any effects, it was more likely to have been 'the recreational‑type effects of relaxation, euphoria, those sorts of effects, not suggestive of psychosis or any of those sorts of effects that would require much higher concentrations'.[115]
[113] ts 245.
[114] ts 245.
[115] ts 246.
As to the level of methylamphetamine found in Mr Davidson's blood, Dr Robertson said:
(a)He estimated that at the time of the incident, Mr Davidson's methylamphetamine level would have been between 0.04 mg/L and possibly 0.05 mg/L. Particularly for a regular user of the drug, the effects of it at this level would be 'minimal if any if the drug was used shortly before the incident'.[116]
(b)Depending on a person's tolerance, where a person displays aggressive psychotic‑type behaviour, generally speaking, it is above concentrations of 1 mg/L or higher.[117]
[116] ts 247.
[117] ts 248.
Under cross‑examination, Dr Robertson explained his definition of 'intoxication' as:[118]
significantly distorting someone's thought process, influencing their behaviours, those sorts of - those sorts of effects.
[118] ts 251.
The prosecutor asked Dr Robertson whether, in his experience, a person who has a psychiatric illness is affected differently by methylamphetamine than a person without a psychiatric illness. Dr Robertson answered:[119]
It's - given methylamphetamine affects the brain - and the - and the neurotransmitters and the balance of neurotransmitters in the brain, I can see how that would be possible. I'm not a psychiatrist, it's outside my field of expertise to - to comment on that but I would understand how that is possible.
[119] ts 252.
Dr Robertson accepted that the long‑term use of methylamphetamine can cause or contribute to mental illness.[120]

Findings from the toxicological evidence

[120] ts 252.

Having regard to the evidence of Dr Joyce and Dr Robertson, there is, in substance, little conflict in their testimony.
While the blood sample taken from Mr Davidson and analysed by the ChemCentre revealed the presence of diazepam and its metabolite, desmethyldiazepam, and tetrahydrocannabinol, I find, having regard to the evidence of both of the toxicological experts and the low levels of each substance, that these substances, individually or in combination with other substances found in Mr Davidson's blood, did not cause or contribute to the alleged offending behaviour. The only drug which had the potential to have affected the offending behaviour was methylamphetamine.
The effects of methylamphetamine upon individuals vary according to the dose of the drug and how habituated a user is to it. The more habituated a user is to the drug, the more of the drug that is required to achieve its effect. The negative effects of methylamphetamine were well described by each of Dr Joyce and Dr Robertson, and their opinions did not materially differ. I find that the effects of methylamphetamine include anger, irritability, impulsivity, aggression and physical violence.
I accept Dr Joyce's evidence, which was, in substance, confirmed by the evidence of Dr Robertson, that at the time of the alleged offences, Mr Davidson's blood concentration of methylamphetamine was around 0.04 mg/L. This level, taken alone, does not point to a case of acute methylamphetamine intoxication. According to both experts, this is a low concentration of methylamphetamine, particularly for a person such as Mr Davidson, who is a long‑term user of the drug. I find that Mr Davidson was not acutely intoxicated by methylamphetamine at the time of the alleged offences. However, this is not to say, as Dr Joyce acknowledged, that methylamphetamine did not have a role in causing or facilitating Mr Davidson's psychiatric state.
Neither Dr Joyce nor Dr Robertson was qualified to provide an opinion as to whether such a low concentration of methylamphetamine would have had a material effect on the behaviour of someone who, like Mr Davidson, was, at the relevant time, also suffering from a mental illness. Dr Joyce testified that from his experience, he had seen aggressive behaviour in persons with mental illness who have low levels of methylamphetamine in their systems. However, while Dr Joyce harbours a suspicion that a low level of methylamphetamine has some causative effect upon such a person's aggressive behaviour, it is only a suspicion and he is unaware of anything in the literature to confirm it.
Both Dr Joyce and Dr Robertson, in effect, deferred to the psychiatrists on the question of what effect the level of methylamphetamine in Mr Davidson's system had at the time of the commission of the offences. The evidence of Dr Joyce and Dr Robertson does not support a finding that at the time of the alleged offences, Mr Davidson was intoxicated by his use of methylamphetamine.
I now turn to the psychiatric evidence.

Mr Davidson's psychiatric history

With the consent of the parties, a folder of documents was tendered in evidence as exhibit 18, which contained records relevant to Mr Davidson's psychiatric history, including discharge letters from Fremantle Hospital and Rockingham Hospital, progress notes taken by the Peel Community Mental Health Service in 2019 and records kept by the Frankland Centre in respect of Mr Davidson's admission to that facility after his arrest for the present offences. These records were made available to both Dr Brett and Dr Pascu. Dr Pascu, as will be seen, did not accept that the discharge summaries were completely accurate. However, the following uncontroversial findings of fact can be made.
In 2000, Mr Davidson was diagnosed with bipolar affective disorder.
In May 2001, he was diagnosed with paranoid schizophrenia.
Between 15 March 2005 and 29 March 2005, he was admitted to Fremantle Hospital Mental Health Unit, where drug‑related problems were diagnosed. Between 3 December 2005 and 19 December 2005, Mr Davidson was once again admitted to Fremantle Hospital Mental Health Unit.
On 21 January 2006, Mr Davidson was diagnosed with schizoaffective disorder at Fremantle Hospital.
In 2010, Mr Davidson was admitted to hospital twice. The first admission was between 25 February and 17 March at Fremantle Hospital Mental Health Unit. The second admission was between 16 December and 21 December at Bentley Hospital Mental Health Unit. During this second admission, he was placed on an alert list, which noted 'aggression when non‑compliant with medications'.

The evidence of Ms Delle‑Grazie and Ms Bennell, along with the CCTV footage from Lotteries House and Rockingham Hospital, shows that, throughout 17 October 2019, Mr Davidson was in an abnormal, agitated and emotional state. He was emotionally upset when he left Ms Bennell's house. When he returned home after visiting Ms Bennell, he was angry, loud, argumentative and in an aggressive mood. In the lead‑up to the relevant attacks on Ms Ugle and Mr Stokes, Mr Davidson shouted at Ms Delle‑Grazie, argued loudly with Mr Stokes, struck Mr Stokes with a tennis racquet and pursued Ms Ugle into the main bedroom.
I accept the unchallenged evidence of Dr Brett that, at the time of the commission of the offences, Mr Davidson was acutely unwell. I find that his mental illness had deteriorated because he was not receiving psychiatric services or his medication, and he was using methylamphetamine.
It is against this background that I turn to the first of the issues that I identified at [4] above.
The legal principles applicable to this issue are set out at [39] - [45] above, and do not require repetition.
As I have explained, the onus is upon Mr Davidson to prove, on the balance of probabilities, that his mental impairment deprived him of the capacity to know that he ought not do the acts which constituted each of counts 1 and 2.
As to count 1, the relevant acts are those described in [69] above. As to count 2, the acts are those described in [72] ‑ [75] above.
The resolution of this issue requires a consideration of the conflicting expert psychiatric evidence of Dr Brett, whose opinion was that Mr Davidson was not deprived of the capacity to know that he ought not do the acts which constituted the offences, and Dr Pascu, whose opinion was that Mr Davidson was deprived of this capacity.
For the reasons below, Mr Davidson has not proved on the balance of probabilities that he was deprived of the capacity to know that he ought not do the acts which constituted the offences.
I begin by making two preliminary observations. First, as a matter of fact, it is no easy thing to prove that a person is, by reason of mental impairment, completely (as opposed to partially) incapacitated from reasoning that an act was, by an objective standard, wrong. As Dr Brett said under cross‑examination, it would take an extreme form of thought disorder to deprive a person of this capacity.
Second, a finding that a person is acutely mentally unwell at the relevant time does not, in and of itself, lead to a conclusion that the person has been deprived of one or more of the relevant capacities in s 27(1) of the Code. There needs to be a cogent explanation as to how the mental illness deprived the person of the relevant capacity.
Dr Brett stated that he could find no evidence to support a finding that Mr Davidson was deprived of the capacity to know that he ought not do the acts which constituted the offences. Dr Brett noted that Mr Davidson was a poor historian. He also noted that there was no good description of Mr Davidson's mental state at the time of the alleged offending. In particular, Mr Davidson described no delusion in respect of either alleged victim, or any phenomena which drove him to act in the way that he did. In Dr Brett's view, Mr Davidson's acts were not driven by psychotic phenomena. A further relevant factor for Dr Brett was that Mr Davidson, when describing the circumstances of count 2, stated to him (and others) that he had, in effect, acted in self‑defence.
The opinion expressed in Dr Pascu's report of 26 June 2020, that Mr Davidson was deprived of the capacity to know that he ought not do the acts the subject of the charges, was expressed as a conclusion. Dr Pascu did not explain her reasons for this conclusion.
At trial, when asked to explain her finding, Dr Pascu gave the answers set out at [205(j) ‑ (l)] and [207] above.
Dr Pascu's opinion was based largely upon her viewing of the CCTV footage of Mr Davidson's police interview on 18 October 2019. She had not seen this footage prior to trial. Dr Pascu noted Mr Davidson's incoherence, thought disorder and that he did not 'really know what [he was] talking about'.
Under cross‑examination, Dr Pascu stated, in substance, that during the police interview Mr Davidson was unable to answer basic questions. She gave as an example of his incapacity to know what he should and should not do that when, in the interview, he was asked by police to stop ranting, he said, 'Yes', but then continued to rant. Dr Pascu added that because Mr Davidson was unable to make a decision to answer questions in the interview, 'he was not able to make a decision about the act he committed'. Further, she said that, in the interview, Mr Davidson displayed an inability to understand what he was talking about.
With great respect to Dr Pascu, I am not persuaded by the reasoning she used to support her conclusion that Mr Davidson was deprived of the capacity to know that he ought not do the acts the subject of the charges. Mr Davidson's behaviour in the police interview was bizarre and reflective of his mental impairment. However, I do not think that it showed that Mr Davidson was, either at the time of the interview or the alleged offences some nine hours earlier, completely deprived of the capacity to know that he should not do the acts the subject of the charges. I note that, during the interview, Mr Davidson is not aggressive or violent. By this time, the level of methylamphetamine in his system would have further reduced.
In my opinion, it is drawing a very long bow to conclude from the matters referred to by Dr Pascu in cross‑examination that there was a complete incapacity on Mr Davidson's part to know that he ought not do the acts the subject of the charges. The example she gave of Mr Davidson's inability to make a decision to answer a question does not demonstrate a complete incapacity on Mr Davidson's part to know that he ought not do the acts the subject of the charges. Nor does the fact that he continued to rant immediately after agreeing to stop ranting, or his apparent inability in the interview to understand what he was talking about.
The State submitted that Dr Pascu was not an objective expert witness by reason of the matters referred to at [216] ‑ [217] above. I do not think that Dr Pascu attempted to minimise Mr Davidson's drug use to bolster her opinion that the acts the subject of the offences were due to his mental illness and not his drug use.
However, at paragraph 33 of her report, she summarised Mr Davidson's discharge summary for an admission between 9 ‑ 16 January 2016. She stated that the diagnosis was 'psychosis secondary to substance use and relapse of his Bipolar Affective Disorder'. This was not the diagnosis in the discharge summary.[229] The principal diagnosis was 'acute psychotic episode likely drug induced (F23 9)'. The discharge summary also noted under the subheading, 'Other conditions', that Mr Davidson had 'Bipolar Affective Disorder (in remission)'. In her evidence, Dr Pascu accepted that she probably should not have summarised the diagnosis in her report in this way. Ms Robinson submitted that this inconsistency was 'a very serious misrepresentation'.[230] I would not go this far, but the error is, to my mind, such that it has given rise to some doubt about the reliability of her opinions.
[229] Exhibit 18, tab 7.
[230] ts 380.
Moreover, I accept Dr Brett's testimony to the effect that there was no evidence to support a finding that Mr Davidson was deprived of the capacity to know that he ought not do the acts which constituted the offences. There was, as Dr Brett observed, no good description of Mr Davidson's mental state at the time of the offending. While the absence of such a description may be a consequence of the traumatic nature of the events, this explanation does not overcome the absence of a good description of his mental state. As Dr Brett stated, Mr Davidson described no delusions regarding Ms Ugle or Mr Stokes, nor any phenomena which drove him to act in the way that he did. I note that, in recounting the circumstances of count 2, Mr Davidson told both Dr Brett and Dr Pascu that, in effect, he acted in self‑defence. It appears that, on 22 October 2019, Mr Davidson told a doctor at the Frankland Centre something similar. A statement to the effect that a person was acting in self‑defence implies a moral justification for their actions. To my mind, this points towards the existence of some capacity for moral reasoning, that is, to know that something is right or wrong by ordinary standards.
I note Ms Farley SC's submission that Mr Davidson's statement should be taken as a justification made in hindsight at a time when Mr Davidson was under treatment. I do not accept this submission. Mr Davidson offered this justification shortly after the commission of the alleged offences at the Frankland Centre close in time to the relevant events. It reflects, in my opinion, his capacity to discern right from wrong at the time of the commission of the relevant offences.
Mr Davidson has not persuaded me that his mental impairment completely deprived him of the capacity to know that he ought not do the acts the subject of counts 1 and 2. I do not accept Dr Pascu's opinion because I am not persuaded by the reasoning which underpins it. In contrast, I found the reasoning of Dr Brett persuasive. In the end, Mr Davidson has not discharged the onus cast upon him to show, on the balance of probabilities, that, as a result of his mental impairment, he was deprived of the capacity to know that he ought not do the acts the subject of counts 1 and 2.
This conclusion is sufficient to decide, adversely to Mr Davidson, the question of his criminal responsibility for the acts which constituted the counts on the indictment. However, in case I am wrong on this issue, I will decide the second issue set out in [4] above, which relates to the operation of s 28(2) of the Code.

Did Mr Davidson intentionally cause himself to become intoxicated or stupefied by methylamphetamine?

I will address this issue on the assumption, contrary to my finding, that Mr Davidson's mental impairment deprived him of the capacity to know that he ought not do the acts which constituted the offences.
As mentioned above, at 2.00 am on 18 October 2019, blood samples were taken from Mr Davidson, the results of which were set out in the ChemCentre report, dated 11 December 2019, which is reproduced at [105] above.
While alcohol, diazepam and tetrahydrocannabinol were detected in Mr Davidson's blood, it is common ground that none of those drugs, either alone or in combination, at the levels detected, were capable of intoxicating Mr Davidson. The only substance capable of intoxicating Mr Davidson was methylamphetamine.
The adverse effects of methylamphetamine are well known to anyone engaged in the criminal justice system. As described by Dr Joyce, methylamphetamine, at sufficient levels, has the capacity to cause impulsivity, loss of self‑restraint and engender agitation, anger and aggression, which may lead to violence, whether or not a person has a mental illness. However, as Dr Brett pointed out, in evidence which was unchallenged, in a person with a mental illness:
(1)Methylamphetamine has potent psychotic properties that can precipitate acute relapses of mental illness.
(2)The drug worsens the effects of the mental illnesses suffered, in this case, by Mr Davidson.
(3)In a person with a major mental illness, methylamphetamine use is 'highly likely' to lead to a relapse of that illness.
There is no dispute that Mr Davidson is a long‑term user of methylamphetamine and that his use of the drug leads to a deterioration in his mental illness, particularly when the illness is untreated.
In the days leading up to the commission of the alleged offences, Mr Davidson was voluntarily using methylamphetamine. On the morning of 17 October 2019, he voluntarily injected himself with the drug. As I have already observed, there is no evidence of the quantity and quality of the drug he used.
What can be said is that, when the blood sample was taken from Mr Davidson at approximately 2.00 am on 18 October 2019, methylamphetamine was detected at a concentration of 0.03 mg/L. The concentration at the time of the alleged offences was approximately 0.04 mg/L.
From the standpoint of Dr Joyce and Dr Robertson, for a person without a mental illness, such a concentration of methylamphetamine is low and inconsistent with acute methylamphetamine intoxication. It was outside the expertise of both Dr Joyce and Dr Robertson to comment on whether the concentration of methylamphetamine found in Mr Davidson's blood had an adverse effect upon his psychiatric illness. To answer this question, both toxicologists deferred to the forensic psychiatrists. It is therefore necessary to return to a consideration of the evidence of Dr Brett and Dr Pascu, which I have already summarised at some length.
I will deal first with the evidence of Dr Brett. In Dr Brett's opinion, Mr Davidson's presentation at the time of the alleged offences was consistent with methylamphetamine‑induced relapse of his mental illness. This was because, consistently with his prior admissions to hospital, his psychotic symptoms improved rapidly. Dr Brett explained that such symptoms, if caused by mental illness, resolve in a matter of weeks, not days. In Mr Davidson's case, Dr Brett observed that Mr Davidson's symptoms and level of thought disorder improved rapidly after his admission to the Frankland Centre, such that, by the afternoon of 22 October 2019, he had gained some insight into his alleged offences. This rapidity of recovery was consistent with Mr Davidson's previous hospital admissions in which methylamphetamine use was noted.
In Dr Brett's opinion, methylamphetamine impacted upon Mr Davidson's mental state at the time of the alleged offences and his intoxication was inextricably linked with his mental disorder.
In Dr Pascu's report, dated 26 June 2020, she acknowledged Mr Davidson's use of illicit substances, stating that it was likely he used illicit drugs to cope with his underlying psychotic symptoms and possibly in an attempt to self‑medicate. Dr Pascu acknowledged that it was difficult to know how much of Mr Davidson's mental state at the time of the alleged offence was altered by his untreated mental illness and how much was due to the added effect of illicit drugs.
In her evidence, Dr Pascu questioned the diagnosis given in some of the discharge summaries tendered to the court that Mr Davidson had drug‑induced psychosis or acute drug intoxication. She was unwilling to accept these diagnoses where there was no confirmatory 'drug screen'.[231] Dr Pascu generalised that discharge summaries were written by junior medical staff and that the information in them might be 'copy and pasted'.[232] Her principal point with respect to the discharge summaries was that a diagnosis of drug‑induced psychosis or acute drug intoxication could not be made in the absence of a 'drug screen'.
[231] Dr Pascu's reference to a drug screen is probably a reference to a urinalysis test which shows the presence (or not) of drugs such as methylamphetamine.
[232] ts 319.
In respect of the ChemCentre's analysis of the blood sample taken from Mr Davidson on 18 October 2019, Dr Pascu said that a concentration of at least 0.1 mg/L is required to be consistent with intoxication, whether a person has a mental illness or not. According to Dr Robertson, the concentration of 0.1 mg/L is the level typically found in recreational users of methylamphetamine.[233]
[233] Dr Robertson's report, 27 October 2020, exhibit 17.
Dr Pascu disagreed with Dr Brett's evidence that patients with major psychiatric disorders can take weeks or months to respond to medication. In her opinion, this was not necessarily the case and she said there were patients for whom antipsychotic medication started working within two or three weeks.

Discussion

I accept that the methylamphetamine concentration found in the blood sample taken from Mr Davidson at about 2.00 am on 18 October 2019 revealed a low level of the drug which, for a person who was not suffering from a serious mental illness, would not have resulted in the person becoming intoxicated. I also accept, based on the evidence of Dr Joyce and Dr Robertson, that Mr Davidson was not acutely intoxicated by methylamphetamine. This finding does not mean that his methylamphetamine consumption had no effect upon Mr Davidson's mental impairment.
I have already found that at the time of the commission of the alleged offences, Mr Davidson was acutely unwell. Against the background of his mental illness, he had voluntarily and intentionally consumed, in the days leading up to the commission of the alleged offences, methylamphetamine, a drug which he appreciated made his mental illness worse.
In my opinion, it is telling that, by 22 October 2019, just three days after the commission of the alleged offences, Mr Davidson was no longer exhibiting the kinds of aggressive and threatening behaviours which marked his conduct on 17 October 2019. The resolution of these symptoms within this time frame strongly suggests that methylamphetamine caused a relapse or exacerbation of his mental illness. I have reached this conclusion against the background that the effects of methylamphetamine dissipate in a much shorter period of time than the effects of major psychiatric disorders such as those suffered by Mr Davidson which, even on Dr Pascu's evidence, take two or three weeks to respond to treatment.
I do not accept Dr Pascu's evidence that Mr Davidson was not intoxicated because his concentration of methylamphetamine in his blood was below a level of 0.1 mg/L. It is unclear to me why this concentration, which Dr Robertson said was typically found in a recreational user of the drug, was as significant as Dr Pascu stated in someone like Mr Davidson who suffered from a serious mental illness.
I prefer the opinion of Dr Brett, that a person with a major mental illness has a lower threshold for becoming psychotic if they use drugs (such as methylamphetamine) than a person who does not have a major mental illness, and that amphetamine use is likely to lead to relapse in a person with a mental illness and that the level of methylamphetamine is less important from a clinical perspective.
As I have noted, Dr Pascu called into question the accuracy of the discharge summaries which noted Mr Davidson's illicit drug use in the absence of a drug screen. In my opinion, having regard to the evidence of Dr Brett, the absence of a drug screen is not a matter of great importance because medical practitioners who treat patients such as Mr Davidson, by reason of their clinical experience, are well able to discern whether a patient is affected by drugs at presentation.
However, in the end, I do not think that anything of significance, relevant to the outcome of this case, turns on the accuracy of the diagnoses given in the discharge summaries, given that there was no dispute that Mr Davidson's presentations to hospital coincided with deteriorating mental health, often manifesting itself in threatening and aggressive behaviours at a time when he was not complying with his medication regime and was using illicit drugs.
I find that Mr Davidson was, at the time of the alleged offences, intentionally intoxicated by methylamphetamine, that is, the methylamphetamine he had consumed over a period of days had an overpowering effect upon Mr Davidson's mind. Assuming that Mr Davidson was deprived of the capacity to know that he ought not do the acts that constituted each of the alleged offences, he has failed to prove that it was his mental impairment and not his intoxication which deprived him of this capacity. On the evidence before me, Mr Davidson's intoxication worsened or exacerbated the effects of his mental illness. As Dr Brett stated, in substance, it is not possible in this case to disentangle the effects of methylamphetamine from Mr Davidson's mental illness. Thus, by reason of s 28(2) of the Code, Mr Davidson is precluded from relying upon s 27(1) of the Code to relieve him of criminal responsibility for counts 1 and 2.

Having found adversely to Mr Davidson in respect of the issues identified in [4] of these reasons, I find that, having regard to s 27(1) of the Code, Mr Davidson was criminally responsible for the acts which constitute the two charges in the indictment. I must now consider the issue of Mr Davidson's intention in each count.

The issue of intention - count 1

It will be recalled that the accused admitted, pursuant to s 32 of the Evidence Act, that, on 17 October 2019, he did an act which endangered the life, health or safety of Ms Ugle. In order for Mr Davidson to be found guilty of count 1, the State must satisfy me beyond reasonable doubt that when he did the act he did it with an intent to harm, as defined in s 304(3) of the Code.
The acts which endangered the health, safety or comfort of Ms Ugle are described at [69] above. As I stated in that paragraph, I am satisfied that Mr Davidson administered multiple blows to Ms Ugle, which were delivered with some force and in circumstances where Mr Davidson was in no way justified in doing what he did. Mr Davidson was, at the time, very angry and highly aggressive. The only reasonable inference open on the facts as I have found them is that at the time Mr Davidson struck Ms Ugle he intended to either unlawfully cause bodily harm to her or to unlawfully endanger her life, health or safety.
I note that Mr Davidson did not allege (nor could he reasonably argue), pursuant to s 28(3) of the Code, that his intoxication by methylamphetamine was such that he was incapable of forming the relevant intention.

The issue of intention - count 2

Mr Davidson has admitted that he caused the death of Mark Stokes and thus is deemed to have killed him. Having rejected Mr Davidson's plea that he was not guilty of count 2 by reason of unsoundness of mind, I find that his killing of Mr Stokes was unlawful. As to the element of intention, it is clear that Mr Davidson was, as I have just said, in a very angry and highly aggressive mood. If anything, he was even more angry and his levels of aggression had increased by the time he attacked Mr Stokes. The unchallenged evidence of Ms Jones was that, at the time Mr Davidson repeatedly struck Mr Stokes with a hammerlike fist motion, she heard him shout, 'I'm going to kill you, you black cunt'. After this statement, Mr Davidson continued to rain blows on Mr Stokes and then placed Mr Stokes' neck in a chokehold. He continued his assault upon Mr Stokes after Mr Stokes fell silent.
Having regard to this evidence, I am satisfied that the only reasonable inference to be drawn is that, at the time Mr Davidson did the acts which led to Mr Stokes' death, he intended to kill Mr Stokes.
Again, I note that Mr Davidson has not argued (nor could he reasonably argue) that at the time he did the acts which caused Mr Stokes' death, he was so intoxicated by methylamphetamine that he was unable to form the relevant intention.

Verdicts

In respect of each of counts 1 and 2, the State has satisfied me beyond reasonable doubt that it has proved each and every element. It follows that Mr Davidson is guilty of each offence.

I certify that the preceding paragraph(s) comprise the reasons for decision of the Supreme Court of Western Australia.
TW
Associate to Mazza J
2 MARCH 2022