Police v Keith Stewart Mouat

[2014] NSWLC 27

Local Court

New South Wales

Medium Neutral Citation:	Police v Keith Stewart Mouat [2014] NSWLC 27
Decision date:	22 December 2014
Jurisdiction:	Criminal
Before:	Heilpern LCM
Decision:	Two counts of the offence of driving under the influence of drugs found not proven beyond reasonable doubt and both charges dismissed.
Catchwords:	CRIMINAL LAW - conflicting expert evidence WORDS AND PHRASES - "under the influence" - Road Transport Act 2013 (NSW), s 112(2)
Legislation Cited:	Road Transport Act 2013 (NSW), s 112(2)
Cases Cited:	Mair v Railway Passengers Assurance Co (1877) 37 LT 356 Sagacious Legal Pty Ltd v Westfarmers General Insurance (No 4) (2010) FCA Vakauta v Kelly (1989) 167 CLR 568
Category:	Principal judgment
Parties:	Police (Prosecution) Keith Stewart Mouat (Defence)
Representation:	Mr Checkley (Solicitor for the Prosecution) Mr Van Dugteren (Solicitor for the Defence)
File Number(s):	2014/00026551
Publication restriction:	Nil

JUDGMENT

1. Mr Mouat was involved in two collisions whilst riding his motorcycle. He was charged with two counts of driving under the influence of drugs. The only issue in this case is whether he was driving under the influence of drugs. The prosecution bear the burden of satisfying the court that he was “under the influence” at the time.

What does “under the influence" mean?

2. This term is not defined by the legislation. The courts have long recognised that there is a line of drug or alcohol use beyond which a person may be proven to be under the influence. In the old case of Mair v Railway Passengers Assurance Co (1877) 37 LT 356, Lord Coleridge CJ mused on the difficulty of considering the point where alcohol or drugs becomes an impediment in the exercising of a person’s mental faculties and where the precise point is:

"…enough to say that there is a point, and it seems to me these words would be satisfied when the influence of intoxicating liquor is found in point of fact to be such as to disturb the quiet and equable exercise of the intellectual faculties of the man who has taken the liquor."

3. In Sagacious Legal Pty Ltd v Westfarmers General Insurance (No 4) (2010) FCA, Rares J stated:

"The determination is one of fact and degree based on the evidence, including, particularly, the observations of those who saw the person at or close to the critical time."

4. The key point is that in this offence the quantity of drugs or alcohol consumed is not in issue – it is the extent to which the drug or alcohol has negatively influenced the defendant’s ability.

The first incident and charge

5. The first incident took place at 08.45 on 5 November 2013. The prosecution evidence was limited by admissibility rules, as they had failed to call any eye witnesses. Accordingly, the only evidence was the defendant’s version. In essence, this was that he had to brake hard to avoid running into a car that pulled out from a car park into his path on a major road, and the motor bike slid out under him. By the time the police arrived he was on a stretcher being taken to hospital. He told the police he had consumed “pot” at 10 pm the previous night, four Valium the previous lunchtime, 17 ml of methadone and two Valium at 6 pm the previous night.

6. About a week later the police contacted the defendant by way of “follow-up”. He told the police officer he had swallowed half a gram of cannabis after the fall, prior to the police attending the scene, as he had it on him and was concerned about getting caught with cannabis in his possession.

Prosecution case on the first incident

7. During submissions, Mr Van Dugteren for the defendant took issue with cannabis being considered part of the allegation. That was because the charge was specified in the information as, “to wit, methadone, diazepam and nitrazepam”. The prosecution took no issue with this submission. A careful reading of s 112(2) of the Road Transport Act 2013 (NSW) limits the prosecution to proving the “influence" alleged is limited to that caused by the drugs named in the court attendance notice, and thus Mr Van Dugteren’s submission is correct.

8. The prosecution rely wholly on the blood analysis certificates and expert’s report by John Andrew Farrar, a consultant forensic pharmacologist employed by the NSW Police Force.

9. Mr Farrar’s conclusion is that the defendant was under the influence of methadone, diazepam and nitrazepam to the extent that his ability to ride a motorcycle was impaired. His view is that benzodiazepine use results in impaired driving and tolerance, with respect to this drug, does not reduce the impairment. Further, his opinion is that the use of methadone and benzodiazapine concurrently increases that impairment. He states at 3.2:

"It is generally safe for such patients to undertake complex psychomotor activities such as driving (Bernard et al, 2009). However, methadone is known to enhance impairment caused by co-consumption of benzodiazepines (Bernard et al, 2009) such as diazepam and nitrazepam."

10. In cross examination at 15:25 he repeated the same assertion regarding the use of benzodiazepines, stating, “…they are known epidemiologically to be exacerbated by co-consumption of methadone.”

11. In essence, the prosecution case relies upon Mr Farrar’s opinion relating to tolerance and co-consumption. At 15:10 in cross-examination he stated that tolerance does not impact significantly on unwanted side effects because:

"[A] dosage of a drug that produces the desired therapeutic effect will also produce effects that are unwanted irrespective of the development of tolerance, tolerance just means you have to take more of the drug in order to produce the desired therapeutic effect, it still continues to provide the unwanted side effects."

12. Mr Farrar was challenged as to both conclusions by Mr Van Dugteren in cross-examination. On the issue of whether a person who is taking a therapeutic dose of benzodiazepines and is a long term chronic user will have their driving ability impaired, Mr Farrar acknowledged that, “there isn’t a perfect linear causal link between them.”

13. I pause to comment that this answer was surprising to me listening to the evidence. After all, Mr Farrar had written in his report, without qualification, at 3.9 – 3.10:

"The concentrations of diazepam and nordiazepam in Mouat’s blood sample are within the therapeutic range for these substances (Bramness et al 2003)…the combined quantities of diazepam and nordiazepam, at the concentrations detected, cause cognitive and psychomotor impairment, and are epidemiologically associated with increased traffic-accident risk (Longo et al, 2001: Bramness et al, 2003: Smink et al 2008)."

14. In cross-examination, Mr Farrar stated these conclusions were drawn from the studies of Longo, Bramness and Smink, and another by Drummer. Each study is referred to in the references section of the report by Mr Farrar. 

15. From this cross-examination, it became apparent that Drummer’s paper was a review of other published papers, and the papers of Longo, Brammness and Smink were based upon epidemiological studies. They looked at a sample of drivers with varying limits, tested following accidents or detection and compared those tests. This means that no persons were actually taken into a laboratory and tested on some sort of reaction or skills machine with varying degrees of benzodiazapines in their blood, allowing for tolerance in chronic long-term users. Thus, in Longo, blood samples from 2500 injured drivers were analysed, and 68 of these tested positive for at least one benzodiazepine. There was a significant linear relationship between benzodiazepine concentration and the culpability of drivers.

16. With respect to Mr Farrar, his conclusions are academically interesting, but can hardly prove, on the basis of the reports he referred to, that this individual was impaired at the time of the first incident. The falsity of this logic can be shown through example. There exists an undoubted truth that younger male drivers are more likely to cause a fatal accident than younger female drivers. However, it would be simply illogical to conclude from that truth, that any one single young male driver was, beyond reasonable doubt, guilty of a charge of dangerous driving causing death.

17. Before leaving Longo’s study, it is interesting to note her reference to other studies:

"Prior research examining the relationship between benzodiazepine use and crash risk has yielded inconsistent results, with some studies finding no significant relationship (Jick et al 1981; Benzodiazepine Collaborative Group, 1993; Leville et al 1994)."

18. Surprisingly, this contradictory evidence did not find its way into the report by Mr Farrar despite it being clear in a paper quoted by him.

19. Further, in Longo, the following passage appears:

"When interpreting these data, it is important to note that there was no information available on driver’s history of bensodiazapine use, such as the dose taken prior to the crash or the frequency of use. Experimental studies have found that a tolerance to the impairing effects of benzodiazapines occurs after chronic use."

20. Perhaps Mr Farrar forgot to mention this when stating with such certainty that tolerance does not have an impact on impairing effects.

21. There was a return to the issue of the impacts of benzodiazapines later in the hearing, and two further papers are referred to by Mr Farrar. The first paper was authored by O’Hanlon, which is referred to in Drummer, but only deals with relatively naïve users of benzodiazapines. The second paper was authored by Verster. Mr Farrar appears to be under the misunderstanding that Verster conducted the tests himself (29:05-29:25). Clearly, Verster did not, and as the title of his study suggests, it is a meta-analysis of other studies. There is no issue of tolerance discussed.

22. Further, Mr Van Dugteren challenged the conclusions in relation to co-consumption of benzodiazepine and methadone. Mr Farrar relied on the Bernard paper for his conclusion in the transcript at 18.5:

"Bernard found though that again epidemiologically if – where it was present with co-consumed, some co-consumed drugs it did cause in a statistical sense an enhancement of impairment of driving."

23. It soon became apparent this research did not test the motor skills or reaction times of those who had consumed both methadone and benzodiazepines. The study referred to by Bernard was again an epidemiological study, and thus of no probative value in assessing this defendant’s level of affectation. Further, and damning of Mr Farrar’s report, it does not support his contention at 3.2 that, “methadone is known to enhance impairment caused by co-consumption of benzodiazepines such as diazepam and nitrazepam.”

24. There is a telling portion of cross-examination of Mr Farrar at 26:35. Mr Van Dugteren asks what effect a concentration of point three milligrams per litre would have in respect to impairment. Mr Farrar answers:

A. Well, if I had that concentration in my bloodstream I would be impaired and some other-

Q. Yes, but you are not a chronic user.

A. That’s correct, and some other people wouldn’t be impaired.

Q. Why would those other people not be impaired at point 3 milligrams per litre?

A. Some of it is caused by tolerance and some of it is caused by biological variation.

25. That passage seems to directly contradict the statements of Mr Farrar in his report and oral evidence. He concedes tolerance of benzodiazapines does exist, and that it, together with biological differences, means that benzodiazapines affects different people differently.

Defence case on the first incident

26. The defence relied on the expert evidence of Dr Robert Weatherby. In addition to the material considered by Mr Farrar, Dr Weatherby had information that the defendant had been treated with methadone and benzodiazapines for some years, and that his general practitioner had stated in a Medical Report to the Roads and Maritime Service (then known as the Roads and Traffic Authority) that the defendant tolerated his current medication without apparent impairment.

27. Dr Weatherby agrees with Mr Farrar that the levels of methadone and benzodiazepines are as expected, given the prescriptions held and the amounts said to have been taken by the defendant.

28. On benzodiazepines, Dr Weatherby states at paragraph six that:

"With long term use of benzodiazepines, tolerance occurs. When tolerance occurs, the dose must be increased to achieve the original effect…tolerance would have developed and it is highly likely that due to the tolerance developed that the impairment of driving skills no longer was occurring."

29. He also comments that Mr Farrer, at 3.15 of his report, states tolerance can exist, but then in Mr Farrar’s final analysis, concludes that the defendant was driving under the influence:

"Mr Farrar has not considered in his final opinion that tolerance has occurred…Therefore as there were no elevated concentrations and it is known that tolerance had developed, the likelihood of any impairment of driving is extremely minimal…the GP…state(s) that no impairment was apparent."

30. Indeed, this is the crux of the dispute between Dr Weatherby and Mr Farrar, as expressed by the latter at 39:35:

"Dr Weatherby believes that one can be tolerant to a drug through chronic use which I agree with…My thesis is that in order for the drugs to have a therapeutic effect there will always be an accompanying, unwanted in this case, psychomotor impairing effect."

31. Dr Weatherby, at 48:50, is highly critical in his evidence of the suggestion that the Bernard study supports the conclusion that the defendant was impaired by the combination of methadone and benzodiazepines:

[M]ost of those studies are of people who are involved in traffic accidents, virtually all of them, and in fact by doing that you’re actually having people who really presumably have most likely been impaired in some way, so when you look at the sort of data you get from that study you’re actually getting a much higher correlation than you otherwise might. If in fact you were to look at the population as a whole….we’re actually getting a lot more examples of people who aren’t having crashes, who are driving unimpaired but do have the presence of these drugs in their body.

Conclusions on the first incident

32. In a criminal matter, it is unusual for expert evidence to be called. It is even more unusual for expert evidence to be so utterly at odds.

33. In my view, based upon the discussion above, and my assessment of the demeanour of the witness when asked difficult questions, I have significant doubts about the reliability of Mr Farrar’s evidence, particularly when compared to that of Dr Weatherby.  He was partisan, and favoured the prosecution case even when it was not supported by the evidence. It is clear that in parts he relied upon published material which simply did not stack up when those articles were actually read. He failed to mention research which pointed in the other direction from his conclusions.

34. His evidence called to mind a passage by Justice Hunt when describing some anticipated evidence in Vakauta v Kelly (1989) 167 CLR 568.

"Will the GIO, instead of referring the plaintiff to its usual panel of doctors who think you can do a full weeks work without any arms or legs, do something useful in this case by sending the plaintiff to a specialist in rehabilitation? I am not usually very impressed with the views of that unholy trinity, Drs Lawson, Revai and Dyball, who have been identified as the defendant's doctors in this case, on the basis that those views are almost inevitably slanted in favour of the GIO by whom they have been retained…"

35. Dr Weatherby was clear in his evidence, made appropriate concessions and was unshaken in cross-examination. He was also in possession of information regarding the defendant’s own doctor’s conclusions, and the length of time that the defendant had been prescribed methadone and benzodiazepines.

36. This is a case where the expert evidence is in direct conflict on two key points. The Judicial Commission of New South Wales Criminal Trials Bench Book at 2-1100 contains a useful summary of the manner in which this is to be approached by the finder of fact. The key points are: that it is not simply a case of choosing between the experts as a matter of “simple preference”; that the onus on the prosecution must be borne in mind; and, the reliability and level of expertise of a particular witness are to be considered.

37. It is necessary to compare the qualifications of Mr Farrar and Dr Weatherby. Mr Farrar has a Bachelor of Science with Honours in Pharmacology from Monash University. He has published papers in peer reviewed scientific journals, although none were presented. He has been involved in research surrounding the effects of drugs on human subjects and metabolic studies, although none of that research was disclosed in this case. He has given lectures at five Australian Universities and has been accepted as an expert in eight Australian jurisdictions.

38. Dr Weatherby has a Bachelor of Pharmacy with Honours, a Master of Science (Pharmaceutical Chemistry) and a Ph.D in Pharmacology. He has been a university professor for decades. He is a member of several professional international organisations and has published numerous papers in peer reviewed journals, although none were presented. He also works for the International Olympic Committee on drug testing.

39. I am not satisfied beyond a reasonable doubt that the defendant was driving under the influence of the stated drugs at the stated time. Clearly, he had been a user for a number of years of both drugs. Mr Farrar’s opinion regarding tolerance is rejected, and I accept that tolerance can occur with long term use, and that this decreases the risk of impairment as a result. Further, the levels of the drugs present in his system are not, of themselves, sufficient to prove beyond a reasonable doubt that he was driving under the influence of the drugs in question.

40. That is because analysis of the research shows that the opposite conclusion is illogical and untenable. In particular, the evidence that a combination of benzodiazapines and methadone increases the impairment is inclusive at best, and certainly inapplicable to prove the conclusions reached by Mr Farrar.

41. The charge relating to the first incident is dismissed.

The second incident and charge

42. The second incident occurred on 5 November 2013 when a dog ran into the path of the defendant’s motorcycle. There was an eye witness to this incident, the owner of the dog, and that evidence suggests that the defendant was not at fault. The defendant was charged with driving under the influence of drugs specified as being methadone, delta-9-tetrahydrocannabinol ("THC"), diazepam and nitrazepam.

Prosecution case on the second incident

43. The prosecution case relies on delta-9 THC being a key ingredient that leads to the opinion that the defendant was driving under the influence. Mr Farrar stated under cross-examination:  

"[I]n the later incident the concentrations of diazepam are low. I’d say certainly would not be great enough to cause impairment  in their own right except perhaps in a naïve user, but in combination with the other drugs present specifically the delta-9 THC I believe that he is impaired."

44. I note, in passing, that this explanation seems to contradict the previous tolerance thesis by Mr Farrar.

45. Regarding the second incident, the first limb of the prosecution case are police observations of the defendant. The attending police officer arrived when the defendant was waiting for the ambulance for significant shoulder injuries. He describes the defendant as follows:

"I observed his skin to be pallid and sweaty, his eyes pinpricked and his speech slow and slightly slurred. He did not appear to be in a great deal of pain despite having possibly dislocated or broken his right shoulder or collar bone. I was unable to make any observations of his co-ordination or balance as he remained on the ground and was stretchered into the ambulance."

46. In his statement to police, the defendant stated:

"I had my methadone dose 33 ml about 10 minutes before the accident at Warrwick’s Pharmacy. The night before I had smoked cannabis in a vaporiser and I had taken three valium the afternoon before about 4 pm and 33 ml of methadone about 4.00 pm the day before. My doctor, Dr Glover has sent a letter to the RTA to say that I am ok on my meds to drive or ride my bike because I have been on them about 10 years. I have a fractured right collar bone, ribs and scapula. I also have grazes to my shoulder and right knee. Ivy has bad grazes to her right arm."

47. The second limb of the prosecution case is the expert evidence of Mr Farrar in exhibit eight.

48. Mr Farrar states at 2.2 that:

"Mouat is described by attending police as having an indifferent and sedated demeanour. Mouat’s pupils were enlarged, his breathing was shallow, his speech was slurred and slow…and his movements were sluggish."

49. Mr Farrar repeats his thesis from the first incident that, “…methadone is known to enhance impairment caused by co-consumption of benzodiazepines (Bernard et al 2009) such as diazepam and nitrazepam.”

50. This statement is not qualified by reference to the epidemiological nature of Bernard’s study, and the casual reader would be forgiven for accepting this statement at face value. This statement is rejected as being unreliable and untenable for the reasons discussed above.

51. The tolerance issue is discussed above and the same reasoning applies to the second incident.

52. The key difference in the second incident is the reliance on cannabis. The defendant stated, and there is no evidence to the contrary, that he swallowed a bud of cannabis in his possession after the accident, before the police arrived. In his statement, the defendant maintained he swallowed the cannabis in an attempt to alleviate his pain.

53. The prosecution case is that the defendant’s cannabis levels in the blood test were not affected by the consumption of the cannabis at the accident scene because that would not have affected the levels of cannabis tested in his blood stream. This was the view expressed during cross-examination at 8:45 by Mr Farrar:

"[C]annabis leaf or cannabis bud does not contain very much at all of the active ingredient that is delta-9 THC. It contains primarily a substance called delta-9 THC carboxylic acid which is then converted into the active component delta-9 THC when it is either burned whilst smoking or when it is baked into cookies and consumed orally but not by direct oral consumption."

54. Farrar then asserted he based this opinion “upon a paper written by Swift and her colleagues…in July 2013.”

55. The cross-examination showed that Swift’s paper calculated average delta-9 THC concentration in police seizures of cannabis over a period of time. But at no time in that research is there any assessment of the levels that can be achieved via the consumption of cannabis by raw consumption. Mr Farrar admits as much at 23:20. When asked about the basis of his opinion that eating raw cannabis does not affect the relevant blood tested levels, he asserted the conclusion was “well known” – 24:20. Yet again, Mr Farrar is taking the general and making it specific, and drawing conclusions that, in my view, do not logically follow.

56. He was later tested on his opinion at 36:5. It was put to Mr Farrar that the blood test occurred 125 minutes after the traffic incident, and that this explained the relevant THC level.

"That is where I disagree because I don’t believe that the consumption of cannabis leaf or bud would produce that concentration of THC…As I’ve said to you twice before I base that on the work of Swift, the concentrations of delta-9 THC in cannabis plant material."

57. Indeed Mr Farrar points specifically to the nub of the disagreement he has with Dr Weatherby on this point at 39:45:

"Dr Weatherby also states that one can consume raw cannabis plant, that being a bud, and cause elevated delta-9 THC levels in the bloodstream as a consequence and in my opinion that would be insignificant."

58. In cross-examination Mr Farrar conceded that there was no rational basis for the conclusion in the COPS entry or in his statement that the defendant’s movements were sluggish – in fact he did not move at all.  Mr Farrar was asked at 35:30:

Q: …are you aware of the circumstances whereby Mr Mouat’s movements were observed?

A: No

Q: Are you aware that he was on the ground after a motor vehicle accident and was removed by an ambulance?

A: No, I’m aware that he, as it states here, he had a possibly broken clavicle or dislocated clavicle.

59. That conclusion is surprising, given that the COPS entry clearly states, “Did not walk at scene. Injured and placed on street”.

Defence expert

60. Dr Weatherby directly challenged the view expressed by Mr Farrar relating to consumption of raw cannabis. At 47:5 he points to hydroponically grown cannabis that is much stronger than the average identified in the seized cannabis referred to in the Swift paper. He clearly states the consumption of raw cannabis, if it occurred as described by the defendant, would have likely led to the elevated levels in the blood test some two hours later.

61. Again, the experts are completely at odds.

62. For the reasons given above at paragraphs 32 to 40, the evidence of Mr Farrar is rejected in favour of the evidence of Dr Weatherby.

63. Further, the observations made by the attending police are just as consistent with serious injury as they are with affection by drugs.

64. In the second incident, there is a reasonable explanation consistent with innocence - the defendant ate the cannabis post-accident and this explains the elevated levels of THC.

65. The second charge is also dismissed.

​Magistrate David Heilpern

22 December 2014

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Decision last updated: 03 June 2015