Blood alcohol 2nd sample — will it be lost?

By Anna Sandiford 29/10/2010


Feeling suitably impressed with the facade, I attended at the Beehive yesterday to speak in front of the Transport and Industrial Relations Select Committee.  Apart from seeing a few familiar faces (from the TV, not that I knew in person), it was quite reminiscent of giving evidence in court except that after our statements, it was no holds barred and they could ask us anything they wanted.

The reason I was there was because I was invited by Patrick Winkler, criminal law barrister specialising in drink driving cases, and Dr Roderick Mulgan, medical doctor and criminal law barrister who had asked me, as a forensic scientist specialising in alcohol cases, for my opinion about proposed changes to the law. We were all at parliament to add our comments about The Land Transport (Road Safety and Other Matters) Amendment Bill 213-1 (2010). Various amendments are being proposed but the one that gives us most concern is Clause 33.

At the moment, the Land Transport Act 1988 says that if Mr Bloggs is stopped for alleged drink driving and he provides a sample of blood for blood alcohol analysis, his sample of blood must be split into two portions.  Both portions are sent to ESR Forensic where one of them is analysed for the Police/Crown and the result is reported. As it stands, there is no way to challenge the blood alcohol result reported by ESR – it is taken as being correct. You cannot ask to look at their casefile and you cannot find out how they reached the result that has been reported; this, I understand, is referred to in law as a ‘conclusive presumption’. The only way to check that the sample has been analysed properly is to request that the second sample be released to an independent analyst so that they can do an analysis on the second portion and then the analytical results from the two separate portions can be compared.

Clause 33 of  The Land Transport (Road Safety and Other Matters) Amendment Bill 213-1 (2010) removes the right for a second sample to be retained.  This means that there would only be one sample and that is the one that will be sent to ESR for analysis.  Once the analysis is completed and reported, there is no way to challenge the result.  This is the same with evidential breath testing devices – the results that are provided by the evidential breath testing instruments are taken to be correct and there is no way to challenge them.

As a scientist, it is unacceptable to me to be asked to believe an analytical result without any recourse to see how that result was achieved – what was the analytical regime, what were the control sample results, when was the last batch of control samples run, what are the results of the duplicate samples, etc.   If the changes described in Clause 33 go unaltered, this means that there will be no way to challenge the results of any of the 30,000+ samples that are analysed by ESR Forensic for blood alcohol content each year.  I know from casework experience that mistakes are made: I had a case a few years ago (not in NZ but in a similar jurisdiction) where the defendant was convinced they were not drink driving and they insisted on having their second sample analysed.  The result of the second analysis came back nearly three times lower than the Police result had been – this sort of difference could not be explained by loss of alcohol through storage or any other means.  After having a look at the Crown’s casefile and the Crown scientist seeing the result obtained by the Defence, it was conceded that the samples at the Crown laboratory had accidentally been mixed up.  I also regularly see blood samples on which the labels are illegible or incomplete.  Simple human nature means that mistakes happen and surely on the basis of simple logic it cannot be assumed that no mistakes occur in a laboratory analysing 30,000+ samples a year.  This is no suggestion that ESR is not doing a good job. Quite the opposite – any lab that can manage that quantity of samples with the degree of reproducibility that they seem to be managing must be doing something right.

I just think that in the interests of fairness, the law should allow for defendants to explore the issues of reliability and reproducibility as they relate to blood alcohol analysis, just as defendants are entitled to review and test the evidence being put forward by the Crown in any other criminal prosecution.  Allowing this transparency would not necessarily mean an increase in independent analyses because:

  • most people who are stopped for drink driving accept that they are over the drink driving limit (although they don’t necessarily accept it at the time they are stopped by the Police)
  • there is currently a provision for the second portion of the blood sample to be analysed, so I’m talking about being allowed to maintain what we already.

However, maintaining the current system where the blood sample is split into two and the second is available for drivers (if they want it) would allow the system to be transparent and give the driving public a more restful mind that if we were to be stopped and charged with drink driving, we would have a way to make sure we were being charged correctly and the blood alcohol results were being fully, fairly and accurately reported.

The other thing is that with just one sample, if it gets damaged, lost or compromised before the analysis is completed then there is no more – prosecution over.


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