Meth driving

How hard is it for a Police officer to determine whether a driver might be off their trolley because of methamphetamine abuse?  Some might say that if you see it often enough, you recognise the signs.
How hard is it for a forensic toxicologist to reconcile different driving behaviours as being attributable to meth use?  Possibly very difficult, if no blood sample is taken.  However, New Zealand’s law now allows for a blood sample to be collected from drivers suspected of driving whilst impaired through drugs (see previous posts: Drug driving and impairment testing, Roadside impairment tests; drug driving, Don’t accept the forensic science at face value).  Which is just as well, given the enormous variation in behaviours that can be exhibited by meth users.
I would expect most people in NZ would think that a driver who was on P (pure methamphetamine) would be tanking down the motorway at 150 kph with the Police in hot pursuit, as per last year’s events involving the accidental death of a courier driver who was caught in the cross-fire between Police and an armed driver. However, an article in last month’s Science & Justice shows just how varied the effects of P can be.
The article’s author, Nikolas Lemos*, writes of two separate cases involving drivers being stopped by Police.
The first case involved a relatively placid, co-operative man who drove somewhat erratically but was slow (only about 30 miles an hour) and was tail-gating the car in front. Police asked him to stop and he did.
The second case involved the Police in a high-speed car chase with a driver and a stolen sports utility vehicle. After racing along roads at speeds in excess of 100 miles an hour, the driver then leapt from the moving vehicle, leaving a female passenger to crash, along with the vehicle, into police cars. Police chased the driver and tried, unsuccessfully, to subdue him with a conductive energy weapon (which I assume means a Taser). After being Tasered (is that a real word?) another two times, he was dragged kicking and screaming into custody.
Two more dissimilar descriptions of P users you couldn’t imagine but the blood methamphetamine concentrations of both drivers were comparable as were their heights and weights. Just goes to show just how unpredictable P can be.

* As the article is behind a subscription wall, the full reference is: Lemos, N. 2009. Methamphetamine and driving. Science & Justice, 49(4), 247-249.  Abstract: Methamphetamine incidence in driving under the influence cases in the City and County of San Francisco is a significant and on-going challenge.  Two methamphetamine positive driving cases are presented herein demonstrating some similarities in observed signs and symptoms and drug blood concentrations but which are also characterised by very different driving styles and behaviours towards the police officers when encountered on the road.

The article also discusses other issues such as the field impairment tests and analytical results.


Don’t accept the forensic science at face value

Here in NZ the Police are now stopping people who they suspect may be driving whilst impaired through the use of drugs. I’ve written before about drug driving and the impairment tests and I again reiterate the importance of not accepting the blood sample analytical results at face value, particularly in relation to cannabis. Lawyers in NZ seem to accept the science as reported by ESR in casework at face value. Whilst I’m not suggesting that ESR mis-reports any science, it must be remembered that the scientists at ESR base their reports on the information provided to them by the Police. Quite often a Defendant will be willing to tell something to their lawyer that they weren’t prepared to tell the Police – for whatever reason. This can have a marked effect on the interpretation.
Rather than leave it to chance for cross-examination in the witness box, lawyers should be asking experts to re-examine the science. Without such re-examination, re-interpretation is left to the scientific knowledge of the lawyers….
I have been unable to find an independent forensic toxicologist in New Zealand – it must therefore be accepted that if the Defence is to have a level playing field in court, funding must be provided for an independent Expert based overseas.
Many people will think that most people who are arrested for any reason are guilty of some crime, so does it really matter whether or not they get Experts to speak for their side of the story? Isn’t it just a waste of taxpayers money? But just remember that anyone can get arrested – wouldn’t you want access to good Experts if you, or one of your family, children or friends was arrested and charged with a criminal offence?

Roadside drug testing; drug driving

One of my earlier posts commented on drug driving, the recent law changes in New Zealand and the new ad campaign in England & Wales.  The answer that everyone would like (apart from the people who actually take the drugs) is a roadside device that can screen, say, saliva for the presence of drugs – the drug equivalent of a handheld breath alcohol testing device.

It is important to understand that one of the reasons it is so hard to produce a device like a breath tester but for drugs is that the blood alcohol level is prescribed in law and can be so prescribed because of the way alcohol behaves once it enters the body.  Although the effects of alcohol vary within and between individuals, there is still a general level upon which the experts agree that people become impaired through alcohol consumption.  The rate at which alcohol is eliminated from the body is also relatively constant.  The same cannot be said for other drugs, particularly if more than one drug is taken at a time.  Concentrations of drugs and metabolites in saliva and blood also are not directly comparable.  It is not always possible for science to provide a perfect answer to a problem within society.  Be assured that the companies developing the technology for roadside drug testing are flat out developing a workable unit for use at the roadside by Police Officers – I’ve seen some of the prototype work and I’m sure they’ll get there in the end.  In the meantime, the new changes to the New Zealand law should, I hope, be successful.

Drug driving and impairment testing

Drug driving is illegal in many countries including New Zealand and the UK.  New Zealand has recently (June 2009) changed the law in order to increase the rate of successful prosecutions .  These changes, which come into force in December 2009, include giving the Police the power to conduct roadside impairment tests.  Such tests were introduced in England & Wales in 2004.  As a forensic scientist working largely for the Defence at that time, these changes resulted in a) more casework coming through our door; and b) more successful prosecutions.  As long as the Police covered off all relevant points it was very unlikely a case would fail.

My involvement was to assess whether or not the various points had been covered.  These included:

  • a witness (including a Police Officer) who could talk about the manner of driving of the Driver at the time in question;
  • the results of roadside impairment tests undertaken by the Driver under the supervision and direction of a specially-trained Police Officer.  If the Officer deemed that the Driver had performed poorly then they had grounds for arrest and transfer of the Driver to the Police Station.
  • once at the Police Station, a medic is required to examine the Driver.  This allows the medic to rule out any medical cause for any impairment observed by the Police Officer at the scene – the Driver usually has to re-do some or all of the impairment tests.  If the medic formed the opinion that the Driver was impaired through the use of drugs, a blood sample could be taken.  Without this opinion the taking of a blood sample was not allowed.
  • the blood sample would be analysed to detect the presence of a range of commonly-encountered drugs (prescription and illegal) that can adversely affect driving performance. Some drug or metabolite would need to be identified in order to confirm that the Driver may have been under the influence of drugs at the time in question.

All of the above had to be in place for a successful prosecution.  The law change in New Zealand seems to be along similar lines but only time will tell how well the Police and the legal system deal with the changes.

Despite the law changes in England & Wales being successful (in my experience at least), the UK government has announced a new ad campaign warning of the dangers of drug driving. The adverts will advise drivers that the Police can spot the signs of whether someone may be under the influence of drugs using the tag line  “Your eyes will give you away.” It’s true of course.  Drugs affect difference people in different ways but can be generalised.  For instance, depressants such as cannabis impair a driver’s perception of distance, time and speed as well as restrict the ability to do two things at once (such as look for traffic and change gear).  Cocaine is a stimulant and can cause people to take risks such as driving at high speed in a dangerous manner.

People cannot control how drugs affect them, particularly when combined, such as cocaine and alcohol.  Time will tell whether the law change in New Zealand helps combat the problem.