An analyst had given evidence. The defence called a professor, a toxicologist, who gave expert evidence in relation to what he said were the possible consequences which could have occurred, having regard to the evidence which the prosecution had given. The possibility arose from the prosecution’s own evidence as to what had happened with the sample of blood, once it had been split into two equal portions of 2 millimetres and placed in vials which were capable of taking 6 millimetres. His evidence was that: ‘if a smaller amount of blood is placed in the vial then there can be too much preservative for equilibrium to occur when it is heated if the space head space is analysed by gas chromatography the extra fluoride will cause the analytical result to show an alcohol level which is in fact too much, that is higher than what is actually in the blood sample.’ The crown court had taken the view that this was all hypothetical.
Held: Forbes J: ‘In my view, to the extent that the Crown Court appear to have regarded his evidence as merely theoretical, it fell into error. Professor Forrester’s evidence that the prosecution analysis of the appellant’s blood sample was not reliable or accurate was based to a significant extent upon the following uncontroversial facts: (1) that the capacity of the sample vials was 6 millimetres; (2) that fluoride was present in the vials as a preservative; (3) that an approximate amount of 2 millimetres of blood had been placed in each sample vial; and (4) that the method of analysis which would have been used to measure the alcohol content of the blood sample was headspace gas chromatography.’ and ‘It was in respect of the foregoing, uncontroversial facts, all of which had been given in evidence, that Professor Forrester gave unchallenged evidence as to his scientific opinion, namely that, given the amount of blood and fluoride in the sample vial, the headspace gas chromatography method of analysis would give a reading which was about 8 per cent too high.’ Keene LJ: ‘It is open to a defendant when charged with excess alcohol, to call evidence to show that the analysis carried out on behalf of the prosecution was not done properly and that the results therefore cannot be relied on.’
Judges:
Forbes J, Keene LJ
Citations:
[2002] EWHC 385 (Admin)
Jurisdiction:
England and Wales
Cited by:
Cited – Dhaliwal, Regina (on the Application Of) v Director of Public Prosecutions Admn 16-Mar-2006
The defendant appealed his conviction for driving with excess alcohol, saying that the court had failed to allow him to raise properly expert doubts as to the prosecution evidence. He sought to challenge the effect of preservatives on the sample of . .
Lists of cited by and citing cases may be incomplete.
Road Traffic
Updated: 14 October 2022; Ref: scu.242944
