Rodi v The State of Western Australia - [2017] WASCA 81

JURISDICTION : SUPREME COURT OF WESTERN AUSTRALIA

TITLE OF COURT : THE COURT OF APPEAL (WA)

CITATION: RODI -v- THE STATE OF WESTERN AUSTRALIA [2017] WASCA 81

CORAM: BUSS P
NEWNES JA
MITCHELL JA

HEARD: 31 JANUARY 2017

DELIVERED : 21 APRIL 2017

FILE NO/S: CACR 95 of 2015

BETWEEN: PAUL JOSEPH RODI
Appellant
AND
THE STATE OF WESTERN AUSTRALIA
Respondent

ON APPEAL FROM:
Jurisdiction              :  DISTRICT COURT OF WESTERN AUSTRALIA
Coram  :EATON DCJ
File No  :IND 495 of 2013

Catchwords:

Criminal law - Appeal against conviction - Possession of cannabis with intent to sell or supply - New or fresh evidence - Where appellant contended at trial that over 900 g of cannabis head material was harvested from two plants for personal use - Where expert evidence that typical naturally grown female cannabis plant can produce between 100 g and 400 g of cannabis head material - Where expert witness had previously given evidence in other trials that typical naturally grown female cannabis plant can produce between 300 g and 600 g of cannabis head material - Where differences in the evidence of the expert witness reflected a genuine change in his opinion - Where defence counsel did not object to the expert evidence adduced by the prosecutor at the trial and defence counsel did not adduce any expert evidence - Whether unavailability of evidence of expert's previous testimony gave rise to a miscarriage of justice

Legislation:

Criminal Appeals Act 2004 (WA), s 30, s 39, s 40
Criminal Procedure Act 2004 (WA), s 42, s 95
Evidence Act 1906 (WA), s 21, s 22, s 32
Misuse of Drugs Act 1981 (WA), s 6(1)(a), s 11, sch V

Result:

Appellant's application dated 3 September 2015 for leave to adduce additional evidence in the appeal granted
Respondent's applications dated 30 September 2015 and 20 October 2015 for leave to adduce additional evidence in the appeal granted
Appellant's application dated 30 January 2017 for leave to amend the grounds of appeal dismissed
Leave to appeal on grounds 1, 2 and 5 refused
Appellant's application for an extension of time to appeal dismissed
Appeal dismissed

Category: A

Representation:

Counsel:

Appellant: In person
Respondent: Mr J A Scholz

Solicitors:

Appellant: In person
Respondent: Director of Public Prosecutions (WA)

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

Abbott v The State of Western Australia [2005] WASCA 42; (2005) 152 A Crim R 186
ARK v The State of Western Australia [2014] WASCA 45
Beamish v The Queen [2005] WASCA 62
CDJ v VAJ [1998] HCA 67; (1998) 197 CLR 172
CFM v The State of Western Australia [2017] WASCA 15
Crowley v Page (1837) 7 C & P 789; 173 ER 344
Director of Public Prosecutions (Nauru) v Fowler (1984) 154 CLR 627
DPJB v The State of Western Australia [2010] WASCA 12
EXF v The State of Western Australia [2015] WASCA 118
Filippou v The Queen [2015] HCA 29; (2015) 256 CLR 47
Gallagher v The Queen [1986] HCA 26; (1986) 160 CLR 392
Hughes v The State of Western Australia [2015] WASCA 164; (2015) 299 FLR 197
Lawless v The Queen [1979] HCA 49; (1979) 142 CLR 659
Lee v The Queen [1998] HCA 60; (1998) 195 CLR 594
McMahon v The State of Western Australia [2010] WASCA 143
Mickelberg v The Queen [1989] HCA 35; (1989) 167 CLR 259
MJH v The State of Western Australia [2006] WASCA 167; (2006) 33 WAR 9
Nicholls v The Queen [2005] HCA 1; (2005) 219 CLR 196
PAH v The State of Western Australia [2015] WASCA 159
R v Birks (1990) 19 NSWLR 677
R v Taufahema [2007] HCA 11; (2007) 228 CLR 232
Rattan v The Queen [1974] HCA 35; (1974) 131 CLR 510
Rinaldi v The State of Western Australia [2007] WASCA 53
Rodi v The State of Western Australia [2014] WASCA 138
Rodi v The State of Western Australia [No 2] [2014] WASCA 233
Sio v The Queen [2016] HCA 32; (2016) 90 ALJR 963
Smith v The State of Western Australia [2014] WASCA 90
Spies v The Queen [2001] HCA 43; (2000) 201 CLR 603
Stanoevski v The Queen [2001] HCA 4; (2001) 202 CLR 115
The Queen's Case (1820) 2 Brod & B 284, 313; 129 ER 976
TKWJ v The Queen [2002] HCA 46; (2002) 212 CLR 124
White v The State of Western Australia [2006] WASCA 62
Wimbridge v The State of Western Australia [2009] WASCA 196

Table of Contents

Buss P's reasons........................................................................................................................ 6
The application for an extension of time
Overview of the State's case at trial
Overview of the appellant's case at trial
The issues at trial
The prosecutor's opening address at trial
Defence counsel's opening statement at trial
The evidence of Detective Senior Constable Bradley Davey
The evidence of Detective Sergeant Christopher Turner
The evidence of Detective Sergeant Andrew Coen
The evidence of the appellant
Other evidence adduced by defence counsel
No expert evidence adduced by defence counsel
The prosecutor's closing address
Defence counsel's closing address
The grounds of appeal
Ground 3: the appellant's application for leave to adduce additional evidence in the appeal
Ground 3: the State's applications for leave to adduce additional evidence in the appeal
Ground 3: should this court grant leave to adduce any of the additional evidence in the appeal?
Ground 3: findings of fact in relation to the credibility and the cogency of the additional evidence of Detective Coen and Ms White
Ground 3: its merits
The merits of grounds 1, 2 and 5
The application to amend the grounds of appeal to add a new ground

Conclusion
Newnes JA's reasons.............................................................................................................. 41
Mitchell JA's reasons.............................................................................................................. 42

Summary
Search of the appellant's residence
Events prior to trial
Conduct of the trial

State opening
Appellant's opening admissions as to possession
State calls Senior Constable Davey
Prosecutor seeks cannabis yield evidence
Detective Sergeant Turner's evidence
Detective Sergeant Coen's evidence
The appellant's evidence at trial
The prosecutor's closing submissions
Conviction and sentence

Ground of appeal 3

Applications to adduce additional evidence
Additional evidence on which the appellant relies
General principles
Character of the additional evidence on which the appellant relies
Significance of the fresh evidence

Proviso
Extension of time in which to appeal
Other grounds of appeal
Late application
Should a retrial be ordered?

Orders

BUSS P: The appellant has applied for an extension of time to appeal against conviction.
On 27 November 2013, the appellant was convicted, after a trial before Eaton DCJ and a jury, of one count in an indictment.
The count alleged that on 14 April 2012, at Madeley, the appellant had in his possession a prohibited drug, namely cannabis, with intent to sell or supply it to another, contrary to s 6(1)(a) of the Misuse of Drugs Act 1981 (WA) (the MD Act).
On 14 April 2014, the appellant was sentenced to 12 months' immediate imprisonment. A parole eligibility order was made.
I would refuse to grant an extension of time. The appeal should be dismissed. My reasons are as follows.

The application for an extension of time

The last date for appealing against conviction was 5 May 2014. The appellant did not file his appeal notice until 2 June 2015. He has filed an affidavit sworn by him on 2 June 2015 in support of his application to extend time.
On 23 August 2015, Mazza JA referred the application for an extension of time to the hearing of the appeal.
The applicable principles governing the exercise of this court's discretion to extend time are set out in Wimbridge v The State of Western Australia [2009] WASCA 196.
The application for an extension of time should be dismissed because, as I will explain, there is no merit in the grounds of appeal.

Overview of the State's case at trial

On 14 April 2012, at about 8.40 am, police officers executed a search warrant, pursuant to the MD Act, at the appellant's home at 11 Eastcliff Street, Madeley. The appellant was not present when the search was undertaken. The police officers located a total of 925.19 g of cannabis.
In a spare bedroom, the police officers located about 371 g of cannabis head material. It was drying on a system of ropes or twine that had been set up like a clothesline on a bed.
In a shower recess, the police officers located about 531 g of cannabis head material. The drug was dry and ready to be bagged.
In a laundry, the police officers located about 29 g of cannabis. It comprised ground cannabis and chunks of head material. The drug was near smoking implements.
The police officers found eight clipseal bags containing cannabis seeds in a laundry cupboard. Digital scales, scissors and clipseal bags were also found in the bathroom which contained the dry cannabis in the shower recess.
There were three cannabis plants, in poor condition, outside the appellant's house.
The State accepted that the appellant had ongoing pain arising from injuries he had suffered and that he 'self‑medicated' by consuming cannabis. However, on the State's case, the quantity of cannabis found in the appellant's home far exceeded any amount required for his personal use.

Overview of the appellant's case at trial

At the trial, the appellant was represented by an experienced criminal defence lawyer.
At the beginning of the trial, defence counsel made three formal admissions on the appellant's behalf pursuant to s 32 of the Evidence Act 1906 (WA).
First, the appellant admitted that at the material time he was living at 11 Eastcliff Street, Madeley. Secondly, he admitted that at the material time he was in possession of the 925.19 g of cannabis in question. Thirdly, he admitted that the drug seized by the police was, in fact, cannabis.
The appellant's case was that he had cultivated the cannabis for his personal use. He had harvested the cannabis from two of the three cannabis plants found by the police officers outside his house. The appellant intended to use the cannabis by ingesting cannabis butter and smoking cannabis. His intended use of the cannabis was for the purpose of relieving his chronic back pain.

The issues at trial

Section 6(1)(a) of the MD Act provides, relevantly, that a person who, with intent to sell or supply it to another, has in his or her possession a prohibited drug commits a crime. The elements of the crime comprise possession of a prohibited drug with the requisite intention.
Cannabis is a prohibited drug.
Section 11(a) of the MD Act provides, relevantly, that, for the purposes of s 6(1)(a), 'a person shall, unless the contrary is proved, be deemed to have in his possession a prohibited drug with intent to sell or supply it to another if he has in his possession a quantity of the prohibited drug which is not less than the quantity specified in Schedule V in relation to the prohibited drug'.
The quantity specified in Schedule V in relation to cannabis is 100 g.
Once the fact of possession by an accused of at least 100 g of cannabis is proved beyond reasonable doubt or admitted, the State has no other onus to discharge. The purpose of s 11(a), in such a case, is to impose on the accused the onus of establishing on the balance of probabilities that, on the whole of the evidence, he or she did not intend to sell or supply any of the cannabis to another. See Abbott v The State of Western Australia [2005] WASCA 42; (2005) 152 A Crim R 186 [4] (Steytler P).
In the present case, the appellant admitted that he was in possession of the 925.19 g of cannabis the subject of the count in the indictment. So, the appellant had the onus of establishing on the balance of probabilities that, on the whole of the evidence, he did not intend to sell or supply any of the cannabis to another. That was the critical issue at the trial.
Another issue, related to the critical issue, was whether the cannabis in question was, as the appellant asserted, wholly derived from two of the three cannabis plants located outside his home.

The prosecutor's opening address at trial

The prosecutor explained to the jury, in her opening address, the elements of the offence created by s 6(1)(a) of the MD Act and the operation of s 11(a) of the MD Act in the context of the State's allegation that the appellant had in his possession a quantity of cannabis (namely 925.19 g) that exceeded the quantity (namely 100 g) specified in Schedule V of the MD Act.
The prosecutor did not refer in her opening address to any proposed evidence about typical yields from cannabis plants.

Defence counsel's opening statement at trial

Defence counsel made an opening statement at the trial.
During the statement defence counsel made the formal admissions which I have set out at [19] above.
Defence counsel told the jury that 'the real issue in this trial is … whether or not [the appellant] had the cannabis in his possession with the intention to sell or supply' (ts 239).

The evidence of Detective Senior Constable Bradley Davey

The State's first witness, Detective Senior Constable Bradley Davey, gave evidence on 25 November 2013.
Detective Davey was questioned in evidence‑in‑chief about the search by police officers of the appellant's home in Madeley. He produced a video recording of the search and physical evidence seized during the search.
Detective Davey said in cross‑examination that, when they searched the appellant's home, the police officers did not find a number of the usual indicia associated with drug dealing; for example, a 'tick list' of outstanding drug debts, multiple mobile telephones, a substantial quantity of cash or CCTV cameras or other security devices. Detective Davey confirmed there was no evidence that the appellant had grown cannabis plants hydroponically. Detective Davey also said the police did not have any evidence that the appellant had ever sold or supplied or agreed to sell or supply any cannabis or other prohibited drug.
The following exchange occurred between defence counsel and Detective Davey in relation to whether the three cannabis plants found, in poor condition, outside the appellant's house could have been the source of the cannabis in question:
Now, of course, you said that there were plants in poor condition out the back of the house?---That's correct.
Three of them?---Yeah.
Would you agree that those plants had been harvested?---They all had little foliage or anything on them. One of them was dead pretty much so ‑ ‑ ‑
So everything had been stripped off?---That's correct, yes.
Okay. And would you agree that, as a detective, it's a relatively simple deduction to say that if you found three dead plants in the backyard and you found shopping bags full of leafy material in the shower with a pair of scissors on the top, wouldn't you say it's a fair enough deduction to think that someone had cut that material from the plants in the back and put it into the bags and taken it into the shower recess?---I'm not a cannabis expert, I obviously deal with search warrants involving cannabis. But the amount of head that was in the shower recess and in the room wouldn't be indicative of three plants, I don't think (ts 286 ‑ 287).
Detective Davey said in cross‑examination that he was not a cannabis expert, but what he saw on the video recording was 'mainly head [material] and dried out' as distinct from leaf and stem material (ts 288).

The evidence of Detective Sergeant Christopher Turner

The State's second witness, Detective Sergeant Christopher Turner, gave evidence on 26 November 2013.
Detective Turner gave evidence‑in‑chief about the search by police officers of the appellant's home. He confirmed in cross‑examination that, when they searched the home, the police officers did not find a number of the usual indicia associated with drug dealing.
Detective Turner said in answer to questions from the prosecutor that about 531 g of 'cannabis head [material] was located in the bathroom'. He added that 'just over 29 g [of cannabis] was located in the laundry' and the material in the laundry was 'cannabis that was ground up but there [were] also chunks of head [material] in it as well' (ts 301).
Detective Turner said in cross‑examination that 'the buds in the bedroom … had a small amount of stem on them … but the 500‑odd grams in the shower was just all head [material]; there was no stem in that, from memory' (ts 304).

The evidence of Detective Sergeant Andrew Coen

The State's third and final witness, Detective Sergeant Andrew Coen, also gave evidence on 26 November 2013.
Detective Coen said in evidence‑in‑chief that he had been a police officer for 18 years. He was responsible for overseeing and generating investigations into predominantly drug related crime (ts 312).
Detective Coen was not one of the police officers who executed the search warrant at the appellant's home. However he said, in response to a question from the prosecutor, that he could 'offer some comment about what was found at the search as a result of the experience [he had] developed from being a police officer' (ts 313). Further evidence was then adduced in relation to his experience:
[W]hat experience have you gained as a result of being a police officer in these matters?---The drug in issue in this matter is cannabis and I've conducted numerous investigations, both short-term and long-term, into cannabis producers and suppliers. And as a result of that, I've developed knowledge as to how cannabis is grown, how it's sold, terminology used, how it's harvested and how it's packaged.
And what's another way - what's other forms in which you've been able to gain knowledge about cannabis, specifically?---Yes, to ‑ to gain my knowledge there's numerous sources. There's reputable books which I make myself aware of and read. We use informants to tell us about how drugs are sold and dealt and used on the street. We intercept telephones to listen to drug dealers and their users communicating. We use listening devices in houses and cars to listen to people involved in drug activity when they don't think anyone's listening. We use undercover officers to go and purchase drugs. I've used all those tools to investigate drug crime. And to give the court an understanding as my ‑ of my exposure to cannabis, I've conducted ‑ I've probably been to about 100 to 200 cannabis grow sites in my career and I've conducted eight long-term investigations into cannabis dealing. When I say a long-term investigation I mean something that lasts more than a month, less than six months. And as a result of that, I've been ‑ I've seized over 2,000 cannabis plants and about 115 kilos of cannabis material.
Thank you. And in terms of the seizure of quantities are you able to give a range of the quantities that you've been involved in seizing?---I've been involved in your small packet dealer of which is 2 grams, which is the ‑ typically the smallest amount you can purchase, up to kilograms up to ‑ it's usually sold in pounds, not kilograms, but multiple pounds. My biggest seizure in recent time has been 50 pounds of cannabis (ts 313 ‑ 314).
Detective Coen said in evidence‑in‑chief that the active ingredient in cannabis is called tetrahydrocannabinol. It is commonly referred to as THC. Tetrahydrocannabinol is present in the 'entire [cannabis] plant' but it is 'most concentrated and in its highest concentrations in the flowering part of the female [plant]'. That is the part of the cannabis plant that growers seek to harvest and users seek to use. It is the 'head part of the plant'. The leaf of the cannabis plant can be smoked but it does not have the same concentration of tetrahydrocannabinol as the head part of the plant (ts 316 ‑ 317).
Before he gave evidence, Detective Coen viewed the video recording of the search of the appellant's home. He said that the cannabis material in the spare bedroom and in the shower recess looked like cannabis head material (ts 316).
The prosecutor asked Detective Coen questions about the quantity of cannabis head material usually derived from a non‑hydroponic female cannabis plant. Detective Coen's witness statement, which was served on the appellant before the trial as part of the State's brief of evidence, did not include any statements or opinions about typical yields of cannabis head material per plant. Defence counsel did not object to the prosecutor's questions. Detective Coen's evidence‑in‑chief on this issue was as follows:
And are you able to say how much cannabis head you might usually find on a plant?---Yes, I can. Through all the cannabis plants I've seized, (indistinct) with growers and also by conducting yield experiments, that's where I seize a cannabis that's nearly ready to be harvested and I actually harvest the cannabis head off it myself to estimate a yield, as a result of ‑ of that knowledge, cannabis plants typically yield between 100 and 400 grams of cannabis head materials.
Thank you. And just to be clear, I'm just - I'm talking about ‑ not hydroponic plants, so you're also talking about non-hydroponic female plants?---Yes. I've done those yield experiments on naturally grown cannabis plants as well. So 100 - on average, 100 is like the lower end of the scale. 400 grams is on the higher end of the scale. It's - it's rare that we see plants with the - with the amount of cannabis head pushing that 300 to 400 gram of the - mark of the scale. It's more to the lower end of the scale.
And, typically, can you identify by size, like, does the plant need to be a certain size to generate a higher yield or does it not work like that?---No. You can ‑ hydroponically, you can get significant yields off very small plants because you can control the - control the conditions and control how the plant grows. With naturally grown cannabis, it's a bit more - it's a bit more difficult to control the yield and the plant's growth, so the - the yields from naturally grown cannabis plants can vary greatly (ts 317 ‑ 318).

The prosecutor asked Detective Coen about the plants outside the appellant's house that were depicted in the video recording. Defence counsel did not object to the questions. The questions and answers read:
[A]re you aware of the amount that was found in this case of head material?---Yes, I added up the amounts on the drug analysis certificates and it was approximately 900 grams - I think 902 grams.
And are you able to make comment with respect to that amount and the plants that you just saw on the video?---Yes. I ‑ I saw two plants on the video and if there was - and there was about 900 grams of cannabis at the house. The comment I'd say to that is I don't think that all the cannabis at the house is from those two plants out the back.
Thank you. And there was a - also a third plant in the background footage that - that wasn't zoomed in on, so when you're talking about the two plants, you're talking about the - the dead one. Is that right?---Yes, that's right.
And then the one that we saw the officer (indistinct) on the ground?---Yes, that's right.
And so, firstly, with the - with the dead one, would it be likely that that was - produced a recent harvest?---I - I wouldn't be able to say how long ago that one produced the harvest. It looks pretty dead.
And in relation to - assuming that the second plant is a healthy plant or much the same as the first one, they all fitted in that bag that was then sealed, are you able to make comment about those two plants and the 900 grams?---Yes. The size of the plants appears to me to be probably one to two foot, so maybe up to 60 centimetres high and in terms of cannabis plants, that's a small to medium size plant and I wouldn't expect a plant that size naturally grown, since they were out the back, to yield on the higher end of that 100 to 400 gram scale. I'd expect them to yield on the lower end of the 100 to 400 gram scale (ts 319 ‑ 320).
As I have mentioned, the items found by the police officers when they searched the appellant's home included digital scales and clipseal bags. Detective Coen said in evidence‑in‑chief that 'digital scales are used [by drug dealers] to weigh amounts of cannabis into deals' (ts 321). He said in cross‑examination that 'the most favoured method of packing cannabis is … clipseal bags' (ts 326).
Detective Coen said in cross‑examination that:
(a)he was an experienced drug investigator (ts 322 ‑ 323);
(b)he does not have a science degree or any qualifications in botany (ts 322);
(c)he was 'just a police officer' (ts 322);
(d)he based his conclusions in relation to the cannabis plants found, in poor condition, outside the appellant's house on their appearance in the video recording (ts 324);
(e)he did not inspect those plants but merely viewed the video recording of them (ts 324); and
(f)he was unable to give an accurate estimate as to the height or size of the plants (ts 324).
Detective Coen gave this evidence in cross‑examination in relation to the cannabis plants found outside the appellant's house:
I believe the cannabis plants out the back have been grown and have been harvested but as to how much of the substance inside is from those plants, I don't know (ts 325).
Defence counsel did not challenge in cross‑examination Detective Coen's evidence‑in‑chief as to the quantity of cannabis head material usually derived from a non‑hydroponic female cannabis plant. Consistently with that approach, defence counsel did not explore with Detective Coen whether he had previously held a different opinion on typical cannabis yields or whether the opinion he had expressed at the trial was generally accepted by those of his colleagues who were experienced drug investigators in relation to cannabis cultivation.

The evidence of the appellant

Defence counsel called the appellant as a witness.
The appellant gave evidence on 26 and 27 November 2013.
The appellant said in evidence‑in‑chief that the cannabis in question was for his personal use; he did not intend to sell any of the drug; the cannabis in question was harvested from two of the plants depicted in the video recording (the third plant having died); he had grown the plants from seeds in pots; and he normally used cannabis to relieve pain in his back caused by injuries suffered at work and in a minor car accident (ts 351 ‑ 356).
The appellant also gave evidence‑in‑chief that not all of the cannabis found by the police officers was 'usable' (some would have been discarded in the trimming and weighing process) and that the cannabis 'would last [him] 12 months' (ts 359).
The appellant said in cross‑examination:
(a)all of the cannabis in question was harvested from the two plants depicted in the video recording (ts 387);
(b)he had grown the two plants from seeds in two pots (ts 387, 404);
(c)that was the first occasion on which he had grown cannabis (ts 388, 421);
(d)he was not making money selling drugs (ts 396);
(e)he had not sourced the cannabis in question from another supplier (ts 396);
(f)he did not use the electronic scales and the clipseal bags to weigh and package cannabis for sale (ts 397);
(g)the 531 g of cannabis head material in the shower recess was not ready to sell: it was ready to make cannabis butter (ts 397);
(h)he was not selling cannabis to customers or suppliers (ts 405);
(i)the cannabis seized by the police officers was not 'all head material', the cannabis included large amounts of stem and leaf material and the head material was 'poor quality' (ts 398 ‑ 400, 402); and
(j)he had intended to discard about 35% of the cannabis (which was leaf) and then package the cannabis head material into 12 bags of about 50 g each and store the material in his freezer (ts 406).
According to the appellant, the two plants depicted in the video recording had taken nine months to grow from seeds to maturity. They were harvested at maturity (ts 404, 448).

Other evidence adduced by defence counsel

Defence counsel called another witness, Paul Hutchinson, who gave evidence as to the appellant's good character.

No expert evidence adduced by defence counsel

Defence counsel did not call any expert evidence (for example, from a botanist) as to the quantity of cannabis head material usually derived from a non‑hydroponic female cannabis plant.

The prosecutor's closing address

In her closing address, the prosecutor relied on Detective Coen's evidence as to the quantity of cannabis head material usually derived from a non‑hydroponic female cannabis plant to attack the appellant's evidence that all of the cannabis in question was for his personal use. She submitted to the jury that the appellant had told lies.
The relevant passage from the prosecutor's closing address reads:
Detective Sergeant Coen said that from a cannabis plant, in his extensive experience, a person might expect to get 100 to 400 grams of cannabis head per plant. He said that naturally growing plants were more likely to be at the lower end of that scale, and hydroponic plants grown under certain conditions were more likely to generate at the higher end of the scale. The stem didn't weigh 130 grams. The stem didn't weigh 330 grams or 340 grams. The fact is … that the evidence that you have from the experts that it would more likely be on the lower scale, that is, somewhere on the lower end of the 100 to 400. Yet here we have 530 grams of cannabis head material that [the appellant] says to you came from one plant.
And you see, [the appellant has] had a long time to think about what he's going to say, and he's got his story pretty good but not quite right. And the fact of the matter is … that there are a couple of lies, and those lies are the crux of what the State says you can use to find that he's unable to satisfy you on the balance of probabilities because it is a lie, it is fanciful, there is no expert evidence that anyone could possibly grow 530 grams of head material on one plant. And therein lies the key. He got that bit wrong.
And then he tried to say, 'Well, some of it was leaf.' How much? Well ‑ and then he attributed about a third of it to leaf material. But that's not the truth. That's another lie. And you've got the benefit of being able to see the cannabis for yourself and all of the police witnesses gave evidence that it was head material.
And importantly, the detective sergeant with over 25 years' experience, Detective Sergeant Turner, said he was the one that packed it. He was the one that handled it. It was all head material. And he was not challenged about whether there could have been a third of that as leaf.
And the reason for that is that it wasn't leaf. And so the evidence that you have is that you have over 500 grams of head material and the expert says [that he has not seen that much head material grown on a cannabis plant] before in his experience. This is a naturally grown plant. Give [the appellant] the benefit of the doubt, maybe 200 grams would be a good crop. But here he is saying he got more than double.
And this is a person who said that he effectively threw in seeds, he didn't germinate them or take really special care with them. Threw in seeds, put on normal fertiliser and watered them once a day. He didn't research how he could possibly grow the best crop that's ever been seen, it was just dumb luck. That's what he would have you believe (ts 4 ‑ 5).
A little later, the prosecutor reiterated her argument in relation to the quantity of the cannabis in question:
And it's not just the cannabis in the bathroom that was so bumper, off the charts, but also the cannabis that was found in the bedroom, an amount that you would expect to be - it still was in the 400 grams, but it certainly wasn't at the lower end, where the expert evidence gave ‑ the expert witness gave evidence that he would expect naturally grown cannabis to belong (ts 9).

Defence counsel's closing address

In his closing address, defence counsel referred to the failure of the police to find, upon searching the appellant's premises, numerous indicia of drug dealing (ts 12 ‑ 13).
Defence counsel asserted that the appellant was not shaken and was not 'caught out' in cross‑examination (ts 13).
Defence counsel made these submissions about Detective Coen's evidence:
Well, this is what the expert said, Detective Sergeant Coen, about the plants … He said that: I've done those yield experiments on naturally growing cannabis plants as well, so 100, on average, 100 is like the lower end of the scale, 400 grams is on the higher end of the scale. It's rare we see plants with the amount of cannabis head pushing about the three to four hundred gram mark. It's just the lower end of the scale (ts 15).
Defence counsel submitted that the appellant was a witness of truth. Mr Hutchinson had given evidence as to the appellant's good character. The jury should be satisfied on the balance of probabilities that the cannabis in question was for his personal use (ts 17 ‑ 19).

The grounds of appeal

Initially, the appellant relied on five grounds of appeal.
On 13 September 2015, Mazza JA:
(a)granted leave to appeal on ground 3 on the understanding that the ground was read as alleging that 'as a result of fresh or new evidence a miscarriage of justice has occurred'; and
(b)referred the application for leave to appeal on grounds 1, 2, 4 and 5 to the hearing of the appeal.
On 30 January 2017 (the day before the hearing of the appeal), the appellant filed and served an application for leave to add an additional ground 6.
At the hearing of appeal, the appellant abandoned ground 4.
I will deal first with ground 3.

Ground 3: the appellant's application for leave to adduce additional evidence in the appeal

By an application in the appeal dated 3 September 2015, the appellant applied for leave to adduce additional evidence in the appeal. The additional evidence comprises the appellant's affidavit sworn 3 September 2015 including the annexures to his affidavit. On 7 September 2015, Mazza JA referred the appellant's application to the hearing of the appeal.
The annexures to the appellant's affidavit comprise:
(a)a transcript of the evidence given by Detective Coen on 29 November 2012 in the District Court in other unrelated criminal proceedings, namely The State of Western Australia v Challis; and
(b)the transcript of the evidence given by Detective Sergeant David Robson on 18 June 2013 in the District Court in other unrelated criminal proceedings, namely The State of Western Australia v Sarinas.
In Challis, Detective Coen was asked whether he was able to estimate 'the average yield of cannabis head material' derived from a non‑hydroponic female cannabis plant (ts 31). He said that, in his experience, the range was '300 to 600 grams' (ts 31). Detective Coen then clarified that his estimate of 300 g to 600 g was dry weight (ts 31). He explained that the yield depended on 'the skill of the grower or [the] growing techniques being used by the [grower]' (ts 31). Detective Coen added that '[t]he genetics of the plant can also determine how much … head material it can produce' and certain plants are grown 'to be able to produce a certain amount of head [material]' (ts 31).
Detective Robson gave evidence in Sarinas that, '[f]rom [his] research', a 'mature cannabis plant' will yield between 300 g and 600 g of cannabis head material (ts 102 ‑ 103). That quantity was dry weight (ts 103). The actual yield per plant can, however, 'vary quite widely with the skill, expertise of a grower' (ts 103). His 'minimum of 300 g of head material per plant' was 'a conservative estimate' (ts 103).

Ground 3: the State's applications for leave to adduce additional evidence in the appeal

By an application in the appeal dated 30 September 2015, the State applied for leave to adduce additional evidence in the appeal. The additional evidence comprises, relevantly, Detective Coen's affidavit sworn 30 September 2015 including the annexures to his affidavit. On 8 October 2015, Mazza JA referred the State's application to the hearing of the appeal.
In his affidavit, Detective Coen said he was 'regularly asked by the Director of Public Prosecutions and colleagues to comment and give advice in relation to [his] knowledge surrounding cannabis cultivation' [4].
He explained the discrepancy between his evidence in Challis and his evidence at trial in the present case in relation to the quantity of dry cannabis head material which a non‑hydroponic female cannabis plant will usually yield, as follows:
10.Shortly after giving typical cannabis yield evidence throughout 2012, I amended my typical cannabis yield evidence by reducing the 300 grams to 600 grams amount to a 100 grams to 400 grams amount.
11.I reduced this estimation as a result of further knowledge I had been acquiring through cannabis yield experiments and from speaking to growers of cannabis more about the subject.
12.After changing my estimation in regards to typical cannabis yields I began inserting a paragraph in statements I completed for the DPP to explain this change in opinion [10] ‑ [12].
Detective Coen annexed to his affidavit:
(a)a witness statement he completed on 7 May 2014 for pending criminal proceedings in The State of Western Australia v Game;
(b)a witness statement he completed on 18 September 2013 for pending criminal proceedings in The State of Western Australia v McCully; and
(c)a witness statement he completed on 31 May 2013 for pending criminal proceeding in The State of Western Australia v Bernhardt.
In each of those witness statements, Detective Coen included:
(a)a provision which reads, 'I have previously given evidence that cannabis plants typically yield between 300 g and 600 g of cannabis head material'; and
(b)a provision which explains why his evidence on this issue has changed. In his affidavit, Detective Coen said:
To this day when I give evidence in the Magistrates and [District] Court I advise the court that in my experience a typical cannabis plant can be expected to yield dry cannabis head weighing between 100 grams and 400 grams [16].
Detective Coen gave oral evidence at the hearing of the appeal. The appellant cross‑examined him.
Detective Coen's evidence in cross‑examination was, relevantly, as follows:
(a)His experience with cannabis plants was predominantly with hydroponically grown plants (ts 58). He had visited about 200 sites where cannabis was grown and, of those, about 20 involved naturally grown cannabis with the balance being hydroponically grown (ts 62 ‑ 63). His experience was that plants yielding very large quantities of cannabis were naturally grown (ts 56).
(b)In late 2012 or early 2013 his opinion on typical yields of cannabis head material per plant changed as a result of additional investigations, experience and research. He formed the view that an estimate of 100 g to 400 g of cannabis head material per plant was a more accurate than 300 g to 600 g (ts 58).
(c)His usual practice is to include his opinion on typical yields in witness statements where the accused has been charged with cultivating cannabis (ts 66 ‑ 67).
(d)His witness statement in relation to the appellant's trial did not include his opinion on typical yields because he would not 'talk about yields in a matter that doesn't involve cannabis plants under cultivation' (ts 67).
(e)He said, in response to a question about why he gave oral evidence at the appellant's trial about typical yields:
If … I'm asked a question in relation to cannabis yields I will answer it, yes, in a court environment (ts 67).
(f)The following questions and answers occurred in relation to the evidence he gave at the appellant's trial about typical yields:
Your description of the plants was not that they were dead, so therefore is that why in the trial you … gave yield estimates?---I believe I gave yield estimates because I was asked the question.
Sure?---I don't think I was expecting to be asked the question from memory. If I didn't have it in my statement it wasn't … a matter which I thought would come up. So as to why I've answered the question in your trial, it was because I was asked the question from the bar table … I was in the witness box and asked a question and I wasn't told not to answer it so I answered it.
So in other words you're unaware that that was going to be asked of you … ?---Yes. Yes. I wasn't aware - - -
Okay?--- - - - that that was going to be asked (ts 68).
(g)His opinion formed in late 2012 or early 2013 that the typical yield is 100 g to 400 g of cannabis head material per plant applies to both naturally grown and hydroponically grown plants (ts 71).
(h)He has seen some naturally grown cannabis plants yield less than 100 g per plant and other naturally grown cannabis plants yield up to 500 g per plant (ts 71). He elaborated:
There are many, many variables, and that range I give of 100 [g] to 400 [g] currently … is given so that when I tell either juries or other colleagues how much a cannabis plant could be expected to yield, they have a - a figure they can work or - or a typical yield that a plant could ‑ could come up with. So I always preface it by saying, if someone said, 'Could [a] cannabis plant yield less than a hundred?' I would say, 'Yes, it's possible.' 'Could it yield more than 400 grams?' 'Yes, that's also possible.'
So you've seen cannabis plants yield over 500 grams, as you just said?‑‑‑I've seen cannabis - - -
Yes?--- - - - plants yield between … 500 [g] and 600 [g], yes. In fact, some plants, I did a yield experiment on fell between that 500 [g] to 600 [g] range.
So it's quite possible that a plant could yield that much, and you wouldn't be surprised?---Yes, that's right. I've never - - -
Because of the variables?---I've never not said that (ts 71 ‑ 72).

By an application in the appeal dated 20 October 2015, the State applied for leave to adduce (further) additional evidence in the appeal. The (further) additional evidence comprises, relevantly, an affidavit of Katherine White sworn 20 October 2015 including the annexures to her affidavit. On 22 October 2015, Mazza JA referred the State's application to the hearing of the appeal.
In her affidavit, Ms White said:
(a)She is a State prosecutor employed by the Office of the Director of Public Prosecutions (WA) (the DPP). She conducted the State's case against the appellant as file manager and trial counsel [1].
(b)She accepts that Detective Coen's evidence at the trial in relation to typical yields of cannabis head material per plant was not contained in his witness statement [4].
(c)On or about 28 October 2013, defence counsel commenced acting for the appellant [5].
(d)She has been unable to find, within the records of the DPP any further statement of Detective Coen referring to the evidence he gave at trial about typical yields or any email or file note from the State to the appellant or defence counsel setting out the evidence about typical yields that Detective Coen would give [5].
(e)On 19 July 2013, she wrote to the Associate of the Chief Judge of the District Court and the appellant (who was then acting in person) indicating that evidence would be adduced from Detective Coen at trial in relation to typical yields of cannabis head material per plant [6]. The letter reads, relevantly:
The prosecution will lead expert evidence from Detective Sergeant Andrew Coen to talk about how cannabis is grown, expected yields from cannabis plants and how cannabis is supplied and used. He will also explain the relevance of the weapons, cash, clip seal bags and scales also located at the property.
(f)At 9.00 pm on 25 November 2013 (being the first day of the appellant's trial), she sent an email to Detective Turner and Detective Coen (and other police officers) [7]. The email reads, relevantly:
During court this morning was advised possession is no longer an issue … So only [require] Chris Turner and Andy Coen. Can you both be at court at 9.45am … Chris you shouldn't be long at all and Andy would [like] to chat before briefly if that's ok … Can you please view the cannabis seized on video/EVR photos to satisfy yourself [it is] primarily head … And question for you whether could come from the 3 half-dead/dead plants outside??
(g)She does not have any recollection of discussing the cannabis yield evidence with Detective Coen or any recollection of discussing with defence counsel the question of cannabis yield or any evidence which Detective Coen might give on that issue. She cannot locate any email, letter or file note recording any discussion of those matters with defence counsel [8].
(h)She believes, on reviewing Detective Coen's witness statement, her letter dated 19 July 2013 and her email of 25 November 2013, that she 'mistakenly assumed that the yield evidence was contained within Detective Coen's [witness statement]' [9]. Although she does not have any recollection of discussing the cannabis yield evidence with Detective Coen, she believes that she may have asked him, on the morning of 26 November 2013, whether the three plants located at the appellant's home 'could be responsible for the dried head material found at the address' [9].
(i)Although she does not have any recollection of discussing with defence counsel the question of cannabis yield or any evidence that might be given by Detective Coen on that issue, she believes that, in accordance with her usual practice, she would have disclosed to defence counsel any information arising out of any discussion she may have had with Detective Coen on that issue [10]. She does recall that when the cannabis yield evidence was adduced from Detective Coen, defence counsel did not object to the evidence or appear to be taken by surprise [10].
Ms White gave oral evidence at the hearing of the appeal. The appellant cross‑examined her.
Ms White's evidence in cross‑examination was, relevantly, as follows:
(a)She 'couldn't say with any accuracy' when she first had any contact with Detective Coen in relation to the trial, but said she would not have had contact with him until the matter was 'confirmed as going to trial' (ts 80 ‑ 81).
(b)She had been the prosecutor in other trials involving cannabis, but she could not recall whether she had previously adduced evidence from Detective Coen (ts 82).
(c)She could not recall having a conversation with Detective Coen or defence counsel about the yield evidence. However, she believed that she spoke to Detective Coen 'just prior to the trial commencing on the second day [26 November 2013], about … the evidence that he may give with respect to a yield' (ts 82).
(d)When asked whether Detective Coen was aware that he would be giving evidence in relation to cannabis yields, she replied:
As I said, and I just want to be careful in the way that I say this, in - in all fairness to you, I don't have an independent recollection of what happened in November 2013, but by looking at some objective facts or some pieces of evidence which I've attached to my affidavit, I'm able to deduce what I think occurred, and that is that I've asked to meet with Detective Coen briefly on the morning of 26 November to discuss, firstly, that it was all head material, once he had reacquainted himself with the video if he needed to, and secondly, whether the plants located at the rear of the property could be responsible for the entirety of that head material, and they're the two points that are raised in my email. Therefore, whilst I don't remember speaking to him, I believe that that's what I did do prior to commencing day two of the trial (ts 87).
(e)She could not recall whether the possible discussion she had with Detective Coen prior to the trial commencing on the second day would have been the first occasion on which she spoke to Detective Coen about the yield evidence. She explained:
I assume that I had thought that the evidence in relation to yield was in his statement, but I obviously was mistaken, and that would have been the first time that I spoke to him directly in relation to whether the plants at the rear of the property could have been responsible for the head material. Otherwise I would have had another note of it (ts 87).
(f)The statement in her letter dated 19 July 2013 to the Associate of the Chief Judge of the District Court and the appellant that evidence would be adduced from Detective Coen at trial in relation to typical yields of cannabis head material per plant was an error. It reflected her mistaken assumption that Detective Coen's witness statement included information about typical cannabis yields (ts 88).
(g)Prior to the commencement of the trial, she did not know the nature of the appellant's defence. In particular, she was unaware that the appellant's defence would involve the assertion that the cannabis head material found by the police officers at his home was wholly derived from the cannabis plants located outside his home. At that stage, cannabis yield evidence did not appear to be relevant. She did not realise until some stage on 25 November 2013 that the issues at the trial would comprise whether the appellant intended to sell or supply the cannabis in question and the source of the drug. She did not know, prior to the completion of the appellant's trial, that Detective Coen had previously given evidence in other cases about typical yields from cannabis plants that was materially different from the evidence he gave at the appellant's trial (ts 92 ‑ 95).

Ground 3: should this court grant leave to adduce any of the additional evidence in the appeal?

Part 3 of the Criminal Appeals Act 2004 (WA) is headed 'Appeals from superior courts' and comprises s 22 to s 35A.
Part 3 creates rights of appeal in relation to criminal proceedings heard and determined in the General Division of the Supreme Court or in the District Court. Rights of appeal against conviction, sentence and any order made as a result of a conviction are available to a person (the offender) who has been convicted of an offence. It is unnecessary to refer to other rights of appeal created by pt 3.
Section 30 applies in the case of an appeal against conviction by an offender.
By s 30(2), unless under s 30(3) this court allows the appeal, it must dismiss the appeal.
Section 30(3) provides that this court must allow the appeal if in its opinion:
(a)the verdict of guilty on which the conviction is based should be set aside because, having regard to the evidence, it is unreasonable or cannot be supported (s 30(3)(a)); or
(b)the conviction should be set aside because of a wrong decision on a question of law by the judge (s 30(3)(b)); or
(c)there was miscarriage of justice (s 30(3)(c)).
By s 30(4), despite s 30(3), even if a ground of appeal might be decided in favour of the offender, this court may dismiss the appeal if it considers that no substantial miscarriage of justice has occurred.
Part 4 of the Criminal Appeals Act is headed 'Provisions applicable to any appeal' and comprises s 36 to s 45.
Section 39(1) provides that an appeal court must decide an appeal on the evidence and material that were before the lower court. By s 39(3), however, s 39(1) does not affect the power of an appeal court to admit evidence pursuant to s 40.
Section 40(1) provides, relevantly:
For the purposes of dealing with an appeal, an appeal court may do any or all of the following -
(a)order the production of any record or thing, whether or not an exhibit, that is or may be relevant to the appeal;
(b)order a witness who would have been compellable at the trial in the lower court, whether or not called at the trial, to attend and be examined before the appeal court;
…
(d)subject to the Evidence Act 1906 section 9, admit the evidence of a witness, including a convicted appellant, who is a competent but not compellable witness;
(e)admit any other evidence.
The discretionary power conferred on this court by s 40(1)(e) to admit 'any other evidence', for the purposes of dealing with an appeal, is not expressly limited or confined. However, the subject matter, scope and purpose of the appeal provisions in the Criminal Appeals Act, and the issues to be resolved in each appeal, will indicate those considerations which are relevant or irrelevant to the exercise of the power. See, generally, CDJ v VAJ [1998] HCA 67; (1998) 197 CLR 172 [108] (McHugh, Gummow & Callinan JJ). The power in s 40(1)(e) must be exercised, in the context of an appeal against conviction pursuant to s 30, having regard to, amongst other things, the relevance of the evidence sought to be adduced in evaluating whether, within s 30(3), this court is of the opinion that the verdict of guilty on which the conviction is based should be set aside because, having regard to the evidence, it is unreasonable or cannot be supported (s 30(3)(a)); or the conviction should be set aside because of a wrong decision on a question of law by the judge (s 30(3)(b)); or there was a miscarriage of justice (s 30(3)(c)).
Although it is highly unlikely that Parliament intended that s 40(1)(e) should be construed as obliterating the distinction developed in the common law courts between the admission of fresh evidence and the admission of new evidence on appeal, the power in s 40(1)(e) is broader than the principles applicable in common law proceedings. See, generally, CDJ [108], [111].
In Rinaldi v The State of Western Australia [2007] WASCA 53, Steytler P (Wheeler & Pullin JJA agreeing) said, in relation to s 40(1)(a), (b), (d) and (e):
While these provisions afford the Court a discretion, which is not expressed to be limited in any way, to do any of the things provided for, it is most improbable that the legislature intended that they 'should be construed in a way that would have the practical effect of obliterating the distinction between original and appellate jurisdiction': CDJ v VAJ (1998) 197 CLR 172 at [111] per McHugh, Gummow and Callinan JJ (dealing with the provisions of s 93A(2) of the Family Law Act 1975 (Cth)) and see also De La Espriella-Velasco [[2006] WASCA 31; (2006) 31 WAR 291] at [150] per Pullin JA. The common law principles have, of course, been developed over many years in order to meet the ends of justice and the considerations giving rise to them will plainly be material to the exercise of the statutory discretion, which must be exercised judicially. While the common law principles touching upon the distinction between new and fresh evidence are not necessarily determinative of the manner of exercise of the statutory discretion, the considerations giving rise to those principles will ordinarily be weighty, so much so that it will be a rare case in which an exercise of the statutory discretion produces a different outcome to that produced by application of the common law principles [84].
At common law, where an accused has been convicted, an appellate court will not allow an appeal, on the basis of new as distinct from fresh evidence, unless the new evidence establishes that the appellant is innocent or the new evidence raises such a doubt that the court is satisfied that the appellant should not have been convicted. See Lawless v The Queen [1979] HCA 49; (1979) 142 CLR 659, 675 ‑ 676 (Mason J); DPJB v The State of Western Australia [2010] WASCA 12 [66] (Owen JA, McLure P relevantly agreeing).
At common law, where an accused has been convicted, an appellate court will not allow an appeal, on the basis of fresh as distinct from new evidence, unless there is a significant possibility that, on the basis of all of the admissible evidence (that is, the fresh evidence and the evidence given at trial) a fact finding tribunal, acting reasonably, would have acquitted the accused. See Gallagher v The Queen [1986] HCA 26; (1986) 160 CLR 392, 399 (Gibbs CJ), 402 (Mason & Deane JJ); Mickelberg v The Queen [1989] HCA 35; (1989) 167 CLR 259, 273 (Mason CJ), 301 ‑ 302 (Toohey & Gaudron JJ).
In ARK v The State of Western Australia [2014] WASCA 45, I made the following observations (Mazza JA agreeing) in relation to this court's approach to and assessment of additional evidence admitted in an appeal:
The appellate court must decide on the relevance of the additional evidence. It must decide on the credibility of oral evidence and on the authenticity of documentary evidence. In some situations, the appellate court must decide whether it believes the additional evidence. In other situations, the appellate court will merely decide whether the evidence is capable of belief, and is likely to be believed, by reasonable people. After deciding on the relevance and credibility or authenticity of the additional evidence, the appellate court will evaluate its cogency in the context of the evidence adduced at the trial. The evidence which forms part of the trial record must be taken by the appellate court in the sense in which, having regard to the verdict, the jury must have accepted it. See Rattan v The Queen [1974] HCA 35; (1974) 131 CLR 510, 518 (Barwick CJ, McTiernan, Stephen & Jacobs JJ agreeing). See also Lawless (665) (Barwick CJ) [139].
In Rattan v The Queen [1974] HCA 35; (1974) 131 CLR 510, Barwick CJ (McTiernan, Stephen & Jacobs JJ agreeing) explained the manner in which an appellate court must approach additional evidence where the court is considering whether a judgment of conviction should be set aside outright in that innocence is shown or the existence of an appropriate doubt is established:
[T]he court will consider all the material itself, forming and acting upon its own belief in, or disbelief of, the evidence, and upon its own view of the facts of the case including the evidence at the trial, though, as I have said, taking the facts as proved at the trial in the sense which having regard to its verdict the jury must have taken them. Of course, if it is concluded that there was a miscarriage in the sense that the court itself is satisfied of innocence or entertains a reasonable doubt as to guilt, there will be no question of a new trial. The verdict of guilty will be quashed and the appellant discharged.
Further, when the material before the court satisfies the court of a miscarriage of this kind, it will not matter that the new material or some part of it is not fresh evidence, in the sense that it was not or could not have been available at the time of the trial. Thus, until the court decides that there is no miscarriage of this kind, it will not need to consider whether or not any part of the new evidence satisfied the criterion of fresh evidence. The court's acceptance that guilt beyond reasonable doubt is not established, means inevitably that to maintain the verdict of guilty would be a miscarriage of justice. Also, as I have already said, it will not matter in such a case that the trial was fair and without blemish (518 - 519).
However, if the appellate court itself is not satisfied of innocence and does not entertain a reasonable doubt as to guilt, or if the appellant's claim is confined to a new trial (and not an outright acquittal), the approach of the appellate court to additional evidence which is fresh, as distinct from new, will be different. In those circumstances, the appellant's case will be that a miscarriage of justice occurred at the trial because the fresh evidence was not before the jury for consideration. See Rattan, where Barwick CJ elaborated:
In this situation, the court must as before decide the credibility and the cogency of the fresh evidence in order to determine whether, when the fresh evidence, if believed by the jury, is taken with the evidence given at the trial in that sense [most] favourable to the accused which reasonable men might properly accept, it is likely that a verdict of guilty would not have been returned. In considering the material before it for this purpose, the element of credibility will be satisfied if the court is of opinion that the evidence is capable of belief and likely to be believed by a jury. The court in this instance will not be directly acting upon its own view of the evidence but rather upon that view most favourable to an appellant, which in the court's view a jury of reasonable men may properly take (519).
In Rattan, Barwick CJ summarised the position as follows:
To sum up, if the new material, whether or not it is fresh evidence, convinces the court upon its own view of that material that there has been a miscarriage in the sense that a verdict of guilty could not be allowed to stand, the verdict will be quashed without more. But if the new material does not so convince the court, and the only basis put forward for a new trial is the production of new material, no miscarriage will be found if that new material is not fresh evidence. But if there is fresh evidence which in the court's view is properly capable of acceptance and likely to be accepted by a jury, and which is so cogent in the opinion of the court that, being believed, it is likely to produce a different verdict, a new trial will be ordered as a remedy for the miscarriage which has occurred because of the absence at the trial of the fresh evidence (520).
I would grant both the appellant and the State leave to adduce additional evidence in the appeal. The additional evidence comprises the affidavit evidence of Detective Coen and Ms White and the oral evidence they gave at the hearing of the appeal. The additional evidence is relevant in evaluating whether, as alleged in ground 3 and the appellant's submissions on that ground, a miscarriage of justice occurred at the trial as a result of:
(a)Detective Coen's opinion evidence at the trial about the quantity of cannabis head material usually derived from a non‑hydroponic female cannabis plant;
(b)Ms White's submissions in her closing address at the trial, based on Detective Coen's opinion evidence at the trial, that the appellant had lied in giving evidence that:
(i)the cannabis in question was for his personal use; and
(ii)he had harvested the cannabis from two of the three cannabis plants found by the police officers outside his house,
and, therefore, the jury should reject his evidence; and
(c)the absence at the trial of evidence as to Detective Coen's previous opinion about the quantity of cannabis head material usually derived from a non‑hydroponic female cannabis plant.

Ground 3: findings of fact in relation to the credibility and the cogency of the additional evidence of Detective Coen and Ms White

As I have mentioned, ground 3 is to be understood as alleging that, 'as a result of fresh or new evidence', a miscarriage of justice has occurred. It is therefore necessary for this court to evaluate the credibility and the cogency of the additional evidence.
Detective Coen and Ms White were honest witnesses. They gave their evidence to the best of their recollection.
I am satisfied, on the basis of Detective Coen's evidence at the hearing of the appeal and on the basis of the other material before this court, that:
(a)Prior to late 2012 or early 2013, Detective Coen was genuinely of the opinion that the quantity of dry cannabis head material which a female cannabis plant would typically yield was between 300 g and 600 g.
(b)In late 2012 or early 2013, Detective Coen changed his opinion on typical yields of cannabis head material per female plant as a result of additional investigations, experience and research.
(c)Since late 2012 or early 2013, Detective Coen has been genuinely of the opinion that the quantity of dry cannabis head material which a female cannabis plant would typically yield was between 100 g and 400 g.
(d)Detective Coen's opinion prior to late 2012 or early 2013, and his opinion after that time, applied to both naturally grown and hydroponically grown female cannabis plants.
(e)Detective Coen's witness statement in relation to the appellant's trial did not include his opinion on typical cannabis yields because it was his practice not to include that information if he was giving evidence in a case that did not involve cannabis plants under cultivation.
(f)On the morning of 26 November 2013, being the second day of the appellant's trial and the day on which Detective Coen was to and did give evidence, Ms White asked Detective Coen, before the resumption of the trial, whether the cannabis head material found by police at the appellant's home could have been wholly derived from the plants located outside his home.
(g)Prior to the commencement of the appellant's trial, Detective Coen was not expecting to give cannabis yield evidence at the trial.
(h)Detective Coen had seen some naturally grown female cannabis plants yield a quantity of dry cannabis head material greater than or less than the typical range. He had seen some plants yield less than 100 g per plant and others yield between 500 g and 600 g per plant.
I am satisfied, on the basis of Ms White's evidence at the hearing of the appeal and on the basis of the other material before this court, that:
(a)Prior to 25 November 2013 (being the first day of the appellant's trial), Ms White had mistakenly assumed that Detective Coen's witness statement included information about the quantity of dry cannabis head material which female cannabis plants typically yield.
(b)At some stage on 25 November 2013 Ms White realised that her assumption in relation to Detective Coen's witness statement was mistaken.
(c)On the morning of 26 November 2013, being the second day of the appellant's trial and the day on which Detective Coen was to and did give evidence, Ms White asked Detective Coen, before the resumption of the trial, whether the cannabis head material found by police at the appellant's home could have been wholly derived from the plants located outside his home.
(d)Ms White's statement in her letter dated 19 July 2013 to the Associate of the Chief Judge of the District Court and the appellant that evidence would be adduced from Detective Coen at trial in relation to typical yields of cannabis head material was an error. It reflected her mistaken assumption that Detective Coen's witness statement included information about typical cannabis yields.
(e)Prior to the commencement of the trial, Ms White did not know the nature of the appellant's defence. In particular, she was unaware that the appellant's defence would involve the assertion that the cannabis head material found by the police at his home was wholly derived from the cannabis plants located outside his home. At that stage cannabis yield evidence did not appear to Ms White to be relevant.
(f)Ms White did not realise until some stage on 25 November 2013 that the issues at the trial would comprise whether the appellant intended to sell or supply the cannabis in question and the source of the drug.
(g)Ms White did not realise until some stage on 25 November 2013 that cannabis yield evidence was relevant to the matters in issue at the trial. It was reasonable for her not to have had that understanding prior to the commencement of the trial.
(h)Ms White did not know, prior to the completion of the appellant's trial, that Detective Coen had previously given evidence in other cases about typical yields from cannabis plants that was materially different from the evidence he gave at the appellant's trial.
Despite Ms White's evidence as to her usual practice in relation to disclosing relevant evidence to defence counsel in the course of a trial, I am unable to make a finding as to whether Ms White informed defence counsel, before Detective Coen gave evidence, of the relevant content of her conversation with Detective Coen on the morning of 26 November 2013.

Ground 3: its merits

The defence counsel who represented the appellant at the trial was an experienced criminal defence lawyer.
The Australian criminal justice system involves a contest between the State or the Crown and the accused. In general, the accused is bound by the conduct of his or her counsel. The accused's counsel has a broad discretion in the conduct of the defence. As Gleeson CJ (McInerney J agreeing) noted in R v Birks (1990) 19 NSWLR 677:
Decisions as to what witnesses to call, what questions to ask or not to ask, what lines of argument to pursue and what points to abandon, are all matters within the discretion of counsel and frequently involve difficult problems of judgment, including judgment as to tactics. The authorities concerning the rights and duties of counsel are replete with emphatic statements which stress both the independent role of the barrister and the binding consequences for the client of decisions taken by a barrister in the course of running a case (683).
See also TKWJ v The Queen [2002] HCA 46; (2002) 212 CLR 124 [8] (Gleeson CJ); R v Taufahema [2007] HCA 11; (2007) 228 CLR 232 [168] (Kirby J).
An apparently rational decision made by the accused's counsel in the course of the trial will not result in an unfair trial or a miscarriage of justice merely because it may appear then or later on appeal that the decision was not carefully considered, was unwise, or produced consequences which operated to the disadvantage of the accused. See Stanoevski v The Queen [2001] HCA 4; (2001) 202 CLR 115 [21] (Gaudron, Kirby & Callinan JJ); TKWJ [16] ‑ [17] (Gleeson CJ), [95] (McHugh J), [107] (Hayne J, Gummow J agreeing).
An appellate court does not examine whether a decision taken by the accused's counsel at the trial was, in fact, taken for the purpose of obtaining a forensic advantage or avoiding a forensic disadvantage. Rather, the appellate court is concerned only with whether counsel's decision is capable of explanation on that basis. That is, could there be any reasonable explanation for the decision? The test is objective in character. See TKWJ [17] (Gleeson CJ), [27] (Gaudron J, Gummow J agreeing), [107] (Hayne J, Gummow J agreeing).
It is necessary, in determining whether there was a miscarriage of justice at the trial, within s 30(3)(c) of the Criminal Appeals Act, for the purposes of ground 3, to evaluate the additional evidence in the context of the whole of the trial record including the manner in which the appellant's case was run at the trial.
I am satisfied, for the following reasons, that a miscarriage of justice did not occur at the trial as alleged in ground 3 and the appellant's submissions on that ground.
First, the appellant bore the onus of establishing on the balance of probabilities that, on the whole of the evidence adduced at the trial, he did not intend to sell or supply to another any of the 925.19 g of cannabis the subject of the count in the indictment. The appellant formally admitted, at the beginning of the trial, that he was in possession of the cannabis in question. Once the fact of possession by the appellant was admitted, the State had no other onus to discharge.
Secondly, the appellant relied on his own evidence at the trial (and the good character evidence of Mr Hutchinson) to prove, on the balance of probabilities, that the whole of the 925.19 g of cannabis was for his personal use and that he had harvested the cannabis from two of the three cannabis plants found by the police officers outside his house. The appellant did not call any opinion evidence from a botanist or other expert as to the quantity of cannabis head material usually derived from a non‑hydroponic female cannabis plant.
Thirdly, defence counsel did not object to Detective Coen giving opinion evidence about typical cannabis yields on the ground that Detective Coen was not qualified (by training, experience or otherwise) as an expert on that topic.
Fourthly, defence counsel did not object to Detective Coen giving opinion evidence about typical cannabis yields on the ground of non‑disclosure or late disclosure of his evidence on the topic.
Fifthly, defence counsel did not apply for an adjournment of the trial on the ground that he was surprised by the opinion evidence given by Detective Coen or that he needed an opportunity to consult other experts about the accuracy or reliability of Detective Coen's opinion evidence.
Sixthly, defence counsel did not challenge in cross‑examination Detective Coen's evidence‑in‑chief as to the quantity of cannabis head material usually derived from a non‑hydroponic female cannabis plant.
However, some of Detective Coen's evidence in examination‑in‑chief and cross‑examination was favourable to the appellant's case. In particular, Detective Coen did not have a science degree or any qualifications in botany; he was 'just a police officer' (although an experienced drug investigator) (ts 322); he did not inspect the cannabis plants found outside the appellant's house, but merely viewed the video recording of them; he was unable to give an accurate estimate as to the height or size of those plants; he believed 'the cannabis plants out the back [had] been grown and [had] been harvested', but he did not know 'how much of the substance inside [the house was] from those plants' (ts 325); and '[w]ith naturally grown cannabis [compared to hydroponically grown cannabis], it's a bit more difficult to control the yield and the plant's growth, so … the yields from naturally grown cannabis plants can vary greatly' (ts 318).
Seventhly, there is a reasonable explanation for defence counsel's decision at the trial not to challenge Detective Coen's opinion evidence about typical cannabis yields and not to apply for an adjournment of the trial.
It is apparent, on an objective appraisal of the trial record (notably, defence counsel's closing address), that defence counsel's strategy at the trial was to endeavour to discharge the appellant's onus of establishing, on the balance of probabilities, that he did not intend to sell or supply any of the cannabis in question to another:
(a)by persuading the jury to accept that the appellant was of good character and a truthful witness, at least in relation to his evidence that the cannabis included about 35% of non‑head material that he would have discarded; the cannabis was for his personal use, for the purpose of relieving his chronic back pain; that he had harvested the cannabis from two of the three cannabis plants found by the police officers outside his home; and that the electronic scales and the clipseal bags were used for an innocuous purpose;
(b)by persuading the jury to accept that the appellant was not a drug dealer, having regard to the failure of the police officers who searched his premises to find a number of the usual indicia associated with drug dealing and to Detective Davey's confirmation that the police did not have any evidence that the appellant had ever sold or supplied or agreed to sell or supply any cannabis or other prohibited drug; and
(c)by emphasising to the jury those parts of Detective Coen's evidence that were favourable to the appellant's case: see [124] above.
Defence counsel was in a position to form a view as to whether the appellant was likely to present as a credible witness.
Eighthly, the grounds of appeal do not allege that defence counsel was incompetent. That is, of course, a heavy burden which is not easily discharged. See the examination of the issue in McMahon v The State of Western Australia [2010] WASCA 143 [25] ‑ [27] (McLure P, Buss JA agreeing & Mazza J relevantly agreeing).
Ninthly, as I have mentioned, Ms White was an honest witness at the hearing of the appeal and she gave her evidence to the best of her recollection.
Also, as I have mentioned, I am satisfied, on the basis of Ms White's evidence at the hearing of the appeal and on the basis of the other material before this court, that:
(a)Prior to the commencement of the trial, Ms White did not know the nature of the appellant's defence. In particular, she was unaware that the appellant's defence would involve the assertion that the cannabis head material found by the police at his home was wholly derived from the cannabis plants located outside his home. At that stage cannabis yield evidence did not appear to Ms White to be relevant.
(b)Ms White did not realise until some stage on 25 November 2013 (being the first day of the appellant's trial) that the issues at the trial would comprise whether the appellant intended to sell or supply the cannabis in question and the source of the drug.
(c)Ms White did not realise until some stage on 25 November 2013 that cannabis yield evidence was relevant to the matters in issue at the trial. It was reasonable for her not to have had that understanding prior to the commencement of the trial.
(d)Ms White did not know, prior to the completion of the appellant's trial, that Detective Coen had previously given evidence in other cases about typical yields from cannabis plants that was materially different from the evidence he gave at the appellant's trial.
Tenthly, as I have mentioned, I am unable to make a finding as to whether Ms White informed defence counsel, before Detective Coen gave evidence, of the relevant content of her conversation with Detective Coen on the morning of 26 November 2013.
However, the appellant did not seek to adduce in the appeal any evidence from defence counsel on that point.
Eleventhly, the appellant did not seek to adduce in the appeal any opinion evidence from a botanist or other expert as to the quantity of cannabis head material usually derived from a non‑hydroponic female cannabis plant.
Twelfthly, it is true that the appellant gave evidence at the trial that the cannabis seized by the police officers was not 'all head material'; the cannabis included large amounts of stem and leaf material; and he would have discarded about 35% of the cannabis (which was leaf) (ts 398 ‑ 400, 402, 406).
However, at the trial Detective Davey said that what he saw on the video recording was 'mainly head [material] and dried out' as distinct from leaf and stem material (ts 288); Detective Turner said that 'the buds in the bedroom … had a small amount of stem on them … but the 500‑odd grams in the shower was just all head [material]; there was no stem in that, from memory' (ts 304); and Detective Coen said that the cannabis material in the spare bedroom and in the shower recess looked like cannabis head material (ts 317).
Thirteenthly, as I have mentioned, Detective Coen was an honest witness at the hearing of the appeal and he gave his evidence to the best of his recollection.
Also, as I have mentioned, I am satisfied, on the basis of Detective Coen's evidence at the hearing of the appeal and on the basis of the other material before this court, that:
(a)prior to late 2012 or early 2013, Detective Coen was genuinely of the opinion that the quantity of dry cannabis head material which a female cannabis plant would typically yield was between 300 g and 600 g;
(b)in late 2012 or early 2013, Detective Coen changed his opinion as a result of additional investigations, experience and research;
(c)since late 2012 or early 2013, Detective Coen has been genuinely of the opinion that the quantity of dry cannabis head material which a female cannabis plant would typically yield is between 100 g and 400 g; and
(d)Detective Coen's witness statement in relation to the appellant's trial did not include his opinion on typical cannabis yields because:
(i)it was his practice not to include that information if he was giving evidence in a case that did not involve cannabis plants under cultivation; and
(ii)prior to the commencement of the appellant's trial, he was not expecting to give cannabis yield evidence at the trial.
Fourteenthly, the additional evidence as to Detective Coen's previous opinion on typical cannabis yields is, from one perspective, new evidence and, from another perspective, fresh evidence.
It is new evidence in that the appellant could have obtained prior to the trial, by the exercise of reasonable diligence and for use at the trial, evidence from a botanist or other expert as to the quantity of cannabis head material usually derived from a non‑hydroponic female cannabis plant.
It is fresh evidence in that the appellant could not have obtained prior to the trial, by the exercise of reasonable diligence and for use at the trial, details of Detective Coen's previous opinion on typical cannabis yields.
However, as I have mentioned, defence counsel did not challenge in cross‑examination Detective Coen's evidence‑in‑chief as to the quantity of cannabis head material usually derived from a non‑hydroponic female cannabis plant. Consistently with that approach, defence counsel did not explore with Detective Coen whether he had previously held a different opinion on typical cannabis yields or whether the opinion he had expressed at the trial was generally accepted by those of his colleagues who were experienced drug investigators in relation to cannabis cultivation. There would have been little or no forensic risk in asking Detective Coen those questions even though defence counsel was unaware of the answers that would be given. On my assessment of his credibility when he gave evidence in the appeal, there is no reason to suppose that Detective Coen would not have given honest answers to any questions of that kind.
Fifteenthly, I will assume (favourably to the appellant but without deciding the point) that there was a breach of the prosecutor's statutory duty of disclosure in relation to Detective Coen's previous opinion about typical cannabis yields. See, generally, s 95 read with s 42 of the Criminal Procedure Act 2004 (WA); PAH v The State of Western Australia [2015] WASCA 159 [122] ‑ [139] (Buss JA, McLure P & Hall J agreeing).
However, even if the additional evidence as to Detective Coen's previous opinion on typical cannabis yields had been available to the appellant at the trial, the evidence of his previous opinion would have been admissible solely as a prior inconsistent statement.
The truth or reliability of the evidence of a witness (including an expert witness) may be impeached by establishing that the witness has made a prior inconsistent statement.
In Western Australia, the law of evidence governing prior inconsistent statements, including the cross-examination of a witness on an alleged prior inconsistent statement and the proof of a prior inconsistent statement, is derived in part from statute (see s 21 and s 22 of the Evidence Act) and in part from the common law.

In considering what the appellant could have discovered by the exercise of reasonable diligence, it is important to bear in mind the unusual manner in which the critical issue emerged during the course of the trial.
Prior to trial, the appellant would not reasonably have anticipated that the State planned to call evidence as to cannabis yields. While there was a passing reference to evidence of cannabis yields in Ms White's letter of 19 July 2013, there had been no disclosure of the substance of any cannabis yield evidence before trial. The appellant and his legal advisers could reasonably have assumed that, in the absence of any disclosure of evidence about yields, the State did not intend to call evidence about cannabis yields at the appellant's trial. That assumption would have been correct, as the reference to cannabis yields in the 19 July 2013 letter was included in error, and Ms White did not plan to call evidence of that kind when the trial commenced. It follows that, prior to trial, the appellant had no reason to make inquiries about the cannabis yield evidence which Detective Sergeant Coen or other police officers had given in other matters.
The cross‑examination of Senior Constable Davies on the first day of the trial alerted Ms White, for the first time, to the fact that the appellant would give evidence that he had grown all the cannabis material from the plants found outside his residence. There was then a rush to address this issue which the State had not previously anticipated. Ms White asked a question in an email sent at 9.00 pm on the night of the first day of trial, and would have received an answer only minutes before the trial recommenced on the following day. If she disclosed the substance of Detective Sergeant Coen's proposed cannabis yield evidence to the appellant's counsel at all, it could only have been in the minutes before the trial re-commenced.
Had matters proceeded in a more orderly way, Detective Sergeant Coen would no doubt have given a written statement of his cannabis yield evidence, which would then have been provided to the appellant. If the statement had been provided after early 2013, it would have been in the form that Detective Sergeant Coen used at the time, which would have disclosed the different evidence he had previously given. However, because of the manner in which issues emerged and were appreciated by counsel during the course of the trial, this did not occur. The appellant was simply presented with Detective Sergeant Coen's cannabis yield evidence with no disclosure of its substance, other than perhaps a brief conversation between counsel just prior to the commencement of proceedings on the second day of the trial. At the time of the trial, Ms White was not aware that Detective Sergeant Coen had given evidence about yields for cannabis plants in other cases which was different from the evidence that he gave in the appellant's trial (appeal ts 95). Detective Sergeant Coen was not expecting to give cannabis yield evidence until just before he was asked to do so.
At the hearing of this appeal and in written submissions, there was some debate as to whether the prosecutor breached an obligation to disclose Detective Sergeant Coen's evidence (both at the appellant's trial and in other matters) and, if so, as to the source of that obligation. It is unnecessary to resolve that question, which raises issues of construction of various provisions of the Criminal Procedure Act 2004 (WA), in order to dispose of this appeal. Whatever the precise scope of the prosecution's disclosure obligations, the fact remains that the substance of Detective Sergeant Coen's cannabis yield evidence was not disclosed to the appellant at any substantial time prior to the testimony being given. The fact that the evidence was adduced without prior warning meant that the appellant had no real opportunity to investigate the evidence which Detective Sergeant Coen had previously given. In the absence of any disclosure of the earlier different evidence, the appellant had no reason to think that it existed. The appellant and his legal representatives had no basis for knowing or suspecting, at the time of the appellant's trial, that Detective Sergeant Coen had given inconsistent evidence in relation to cannabis yields in earlier trials.
The manner in which Detective Sergeant Coen's cannabis yield evidence was adduced in the appellant's trial, and the non‑disclosure of the evidence which Detective Sergeant Coen had previously given, meant that the appellant could not have discovered the earlier different evidence by the exercise of reasonable diligence. The evidence of Detective Sergeant Coen's previous different evidence about cannabis yields in other trials is properly classified as fresh evidence in these unusual circumstances.

Significance of the fresh evidence

For the following reasons, the fresh evidence is at least capable of calling into question an important aspect of the State's evidence, which was potentially influential in the jury's assessment of the appellant's evidence. In my view, there is a significant possibility that the jury, acting reasonably, would have acquitted the appellant if the evidence of Detective Sergeant Coen's previous different evidence about cannabis yields in other trials had been before it at the appellant's trial.
Detective Sergeant Coen was put forward as a 'drug expert in the Western Australian Police Force' (ts 236). After referring to his experience, Detective Sergeant Coen said that non-hydroponic female cannabis plants typically yield between 100 g and 400 g of cannabis head material. He said that 100 g was on the lower end of the scale and 400 g on the higher end of the scale. His evidence was that it was rare to see cannabis head pushing the 300 g to 400 g mark of the scale, while noting that yields from naturally grown cannabis plants can vary greatly (ts 317 ‑ 318).
Detective Sergeant Coen's evidence was that he did not think that all the cannabis in the house was from the two plants located at the rear of the appellant's house. He said that the plants appeared, from his viewing of video footage, to be up to 60 cm high, which was a small to medium cannabis plant. Detective Sergeant Coen's evidence was that he would not expect the plants to yield on the higher end of the 100 g to 400 g scale, and would expect the yields to be on the lower end of that scale (ts 319 ‑ 320).
The fact that Detective Sergeant Coen had, prior to the appellant's trial, given evidence that he had experienced a range of 300 g to 600 g of head material to be found on a naturally grown female cannabis plant was a potentially very important piece of evidence for the appellant. The 925.19 g of cannabis head material which the State alleged to be in the appellant's possession was well within the 600 g to 1,200 g range which Detective Sergeant Coen's earlier evidence suggested two mature naturally grown female plants would typically produce. It stood well outside the range indicated by Detective Sergeant Coen in the appellant's trial. The previous evidence constituted a prior inconsistent statement, admissible under s 21 of the Evidence Act 1906 (WA), which was capable of undermining the credibility of the different evidence which Detective Sergeant Coen gave in the appellant's trial.
That evidence was not only capable of leading the jury to reject this aspect of Detective Sergeant Coen's testimony. The extent of the change in Detective Sergeant Coen's position was dramatic. The lower end of the range was reduced to a third of the previous estimate. The upper third of the 300 g to 600 g range now falls outside the 'scale' to which Detective Sergeant Coen referred in his evidence at the appellant's trial. Detective Sergeant Coen gave evidence in the appellant's trial that it was 'rare to see' cannabis head pushing the 300 g to 400 g mark of the scale. He gave that evidence despite having previously experienced a range of 300 g to 600 g of head material. The degree of the change in his evidence, and the general statement of the reasons for the change, was capable of calling into question the existence and extent of Detective Sergeant Coen's expertise to give opinion evidence about the yields of head material produced by cannabis plants. This material showed the existence of a potentially fertile ground for cross‑examination of a witness giving significant evidence for the State.
That this was so is illustrated by the weaknesses in this aspect of Detective Sergeant Coen's evidence which emerged on the appellant's cross‑examination of Detective Sergeant Coen in the appeal. The evidence of Detective Sergeant Coen on appeal makes it clear that he cannot exclude a naturally grown cannabis plant yielding up to 600 g of head material, and that he saw such a plant in one of his experiments. The unsatisfactory basis for the opinion expressed at the appellant's trial was revealed. It appears that Detective Sergeant Coen's initial experience was based on what he was told - the training he was given - by other officers. The effect of Detective Sergeant Coen's evidence is that what he was told in training did not match his experience, which was predominantly with hydroponically grown plants. Detective Sergeant Coen's experiments were not of a breadth which would enable him to make a reliable judgment in relation to the limits of yields obtainable from naturally grown cannabis plants. He had sampled only an unstated number of naturally grown plants, some of which produced results in the 500 g - 600 g range, from one location on one occasion.
The prosecutor's closing submission included the statement:
And so the evidence that you have is that you have over 500 grams of head material and the expert says not seen before in his experience.
Detective Sergeant Coen's evidence in this appeal makes it plain that this statement is incorrect. If evidence adduced in this appeal had been available at trial, it would not have allowed that submission to have been made at trial.
The absence at the appellant's trial of evidence of Detective Sergeant Coen's previous testimony deprived the appellant of an opportunity to attack Detective Sergeant Coen's cannabis yield evidence. This gave rise to a miscarriage of justice. Detective Sergeant Coen's cannabis yield evidence was a powerful indicator that the appellant was lying about harvesting all the cannabis from the two plants at the back of his house. It was emphasised forcefully in the prosecutor's closing submissions. The appellant's counsel was unable to effectively challenge the evidence in cross‑examination, which would not have been the case if the evidence of Detective Sergeant Coen's previous testimony, and the reasons for his change of views, had been available at trial.
In this appeal, the State relies on the fact that the appellant's trial counsel did not object to the leading of Detective Sergeant Coen's cannabis yield evidence. That is not a factor to which any weight can be attached. It may be relevant to considering whether late or no disclosure of evidence which Detective Sergeant Coen actually gave resulted in a miscarriage of justice. However, counsel could not raise an objection by reference to information of which he was entirely unaware, and which was not reflected in Detective Sergeant Coen's evidence.

Proviso

In my view, the absence of evidence of Detective Sergeant Coen's previous testimony deprived the appellant of a fair chance of acquittal at his trial. The appellant's evidence about having harvested the cannabis head material from two plants for his personal use was not inherently implausible. A challenge to Detective Sergeant Coen's evidence, employing his prior inconsistent evidence, had real potential to impact on the jury's assessment of the appellant's account. The court cannot be satisfied that no substantial miscarriage of justice has occurred in those circumstances.[14]
[14] Filippou v The Queen [2015] HCA 29; (2015) 256 CLR 47 [15]; White v The State of Western Australia [2006] WASCA 62 [193]; Hughes v The State of Western Australia [2015] WASCA 164; (2015) 299 FLR 197 [65].

Extension of time in which to appeal

The appellant requires an extension of time in which to appeal. Where there has been a lengthy delay in filing an application for leave to appeal, the court requires exceptional circumstances to be established before an extension of time will be granted, unless it can be shown that there will be a miscarriage of justice if an extension is not granted.[15]
[15] EXF v The State of Western Australia [2015] WASCA 118 [5], and cases cited therein.
I would grant that extension. Although there was a significant delay in instituting the appeal, the appellant acted reasonably promptly after receiving the transcripts of Detective Sergeant Coen's evidence in the earlier case. He could not reasonably have instituted an appeal based on new material before he had seen the relevant material. Further, refusal of an extension of time in which to appeal would perpetuate a miscarriage of justice. I would grant an extension of time in which to appeal in these circumstances.

Other grounds of appeal

I would not grant leave to appeal on any of the other proposed grounds, which in my view have no reasonable prospect of success. Given that I would allow the appeal on the basis of the miscarriage of justice identified above, my reasons for refusing leave on the other proposed grounds can be expressed in brief terms.
Proposed ground 1 contends that the appellant should have been charged with cultivating a prohibited plant, under s 7(1)(a) of the Drugs Act, rather than possession of a prohibited drug with intent to sell or supply to another, under s 6(1)(a) of that Act. There is no merit in that ground. The fact that the appellant cultivated the plants from which prohibited drugs found in his possession were harvested provides him with no defence to a charge under s 6(1)(a) of the Drugs Act.
Proposed ground 2 complains that the appellant has been doubly punished, having previously been convicted in the Magistrate's Court of cultivating the plants found at the back of his house and being in possession of cannabis. The charge of simple possession related to bags of cannabis seeds located in the appellant's laundry cupboards. He was convicted of those offences on 24 November 2014, and received fines. It has not been demonstrated that either of those charges related to the cannabis head material which was the subject of the charges before the District Court. No issue of autrefois convict arises in those circumstances, and the appellant has not been punished twice for possession of the cannabis which is the subject of this appeal.
Proposed ground 4 was abandoned at the hearing of the appeal, and it is therefore unnecessary to say anything about that ground.
Proposed ground 5 contends that the trial judge failed to abort the trial after the prosecutor had spoken to Detective Sergeant Coen during a break in proceedings, while Detective Sergeant Coen was under cross‑examination. The appellant's trial counsel applied for the trial to be aborted when proceedings resumed. The evidence of Detective Sergeant Coen was that he had spoken to the prosecutor but not about anything concerning the case (ts 341 - 343). While it was unwise for counsel to have spoken to her witness at all while he was under cross-examination, due to the unfortunate appearance it created, the occurrence of a discussion about matters not associated with the appellant's case did not give rise to any miscarriage of justice.

Late application

At 4.00 pm on the day before this appeal was listed to be heard, the appellant filed an application in an appeal seeking leave to add a ground of appeal and leave to adduce additional evidence in the appeal.
I am not persuaded that the application should be granted. The appellant's approach ignores the rules which require the preparation of grounds and submissions well in advance of the hearing of the appeal. The appellant has not given evidence explaining why the application was made so late. The proposed new ground does not appear to have any substantial merit. Further, it is unnecessary to deal with the proposed new ground to conclude that the appellant's appeal should be allowed. In these circumstances, I would dismiss the application in an appeal filed on 30 January 2017.

Should a retrial be ordered?

The principles governing the exercise of the discretion to order a new trial were stated in Director of Public Prosecutions (Nauru) v Fowler:[16]
The power to grant a new trial is a discretionary one and in deciding whether to exercise it the court which has quashed the conviction must decide whether the interests of justice require a new trial to be had. In so deciding, the court should first consider whether the admissible evidence given at the original trial was sufficiently cogent to justify a conviction, for if it was not it would be wrong by making an order for a new trial to give the prosecution an opportunity to supplement a defective case … Then the court must take into account any circumstances that might render it unjust to the accused to make him stand trial again, remembering however that the public interest in the proper administration of justice must be considered as well as the interests of the individual accused.
[16] Director of Public Prosecutions (Nauru) v Fowler (1984) 154 CLR 627, 630.
Unless the interests of justice require the entry of an acquittal, an appellate court should ordinarily order a new trial of a charge where a conviction in respect of the charge has been set aside but there is evidence to support the charge.[17]
[17] Sio v The Queen [2016] HCA 32; (2016) 90 ALJR 963 [75]; Spies v The Queen [2001] HCA 43; (2000) 201 CLR 603 [104].
Ordinarily, it would be appropriate to order a retrial in a case of this kind. However, the appellant has served the whole of the sentence imposed on him in respect of the offence of which he was convicted. Given that he has already served any sentence which could reasonably be imposed on any re-trial, it would be unjust to make the appellant stand trial again.
However, the appellant admitted being in possession of about 925 g of cannabis. That offence against s 6(2) of the Drugs Act was an alternate verdict at trial.[18] I am satisfied that the jury must have been satisfied of the facts that prove that the appellant was guilty of an offence against s 6(2) of the Drugs Act. It is appropriate for this court to exercise its power to substitute a conviction of that offence.[19] Given the time the appellant has already served in custody, it is inappropriate for any further penalty to be imposed. At the hearing of the appeal, both parties agreed that this was the appropriate outcome if the appeal succeeded on ground 3.
[18] Section 10(a) of the Drugs Act.
[19] Section 30(5)(c) of the Criminal Appeals Act.

Orders

For the above reasons, I would make the following orders:
1.The appellant's application for an extension of time in which to appeal is granted.
2.The appellant's application in an appeal dated 3 September 2015, seeking leave to adduce additional evidence in the appeal, is granted.
3.The respondent's applications in an appeal dated 30 September 2015 and 20 October 2015, seeking leave to adduce additional evidence in the appeal, are granted.
4.The appellant's application in an appeal dated 30 January 2017, seeking leave to add a ground of appeal and adduce additional evidence in the appeal, is refused.
5.Leave to appeal on proposed grounds 1, 2, 4 and 5 is refused.
6.The appeal is allowed.
7.The appellant's conviction on District Court indictment 495 of 2013 of possession of a prohibited drug, namely cannabis, with intent to sell or supply to another, contrary to s 6(1)(a) of the Drugs Act, is set aside.
8.Judgment of conviction is entered for the following offence: That on 14 April 2012 at Madeley the appellant had in his possession a prohibited drug, namely cannabis, contrary to s 6(2) of the Drugs Act.
9.No penalty is imposed in respect of the offence referred to in order 8.