Caution in Use of Hair Samples to Test Alcohol
The court considered the extent to which reliance could be placed on tests of hair samples for alcohol in care proceedings.
Held: Such evidence should be used with caution: ‘(i) When used, hair tests should be used only as part of the evidential picture. Of course, at the very high levels which can be found (multiples of the agreed cut off levels) such results might form a significant part of the evidential picture. Subject to this however, both Professor Pragst and Mr O’Sullivan agreed that ‘You cannot put everything on the hair test’; in other words that the tests should not be used to reach evidential conclusions by themselves in isolation of other evidence. I sensed considerable unease on the part of Professor Pragst at the prospect of the results of the tests being used, other than merely as one part of the evidence, to justify significant child care decisions;
(ii) Because of the respective strengths and weaknesses of each of the tests (for EtG and FAEEs), if hair tests are going to be undertaken, both tests should be used. Research has shown that the tests can produce conflicting results;
(iii) The results produced by the tests should be used only for the purposes of determining whether they are or are not consistent with excessive alcohol consumption by use of the cut off levels referred to in paragraph 20 above. If they are not – in other words if the concentration found is below the generally recognised cut-off levels – the results are consistent with (indicative of) abstinence/social drinking. If the results are above the generally recognised cut-off levels, they are consistent with (indicative of) excessive alcohol consumption. Further, as referred to earlier in this judgment, at these cut off levels the research evidence suggests that 10% of the results will be false positives. The tests cannot establish whether a person has been abstinent both because the non-detection of either EtG or FAEEs does not mean that the subject has not consumed alcohol and also because the detection of either at volumes below the cut off levels referred to above below does not mean that they have. Finally, on this point, the tests are not designed to establish abstinence or social drinking;
(iv) The current peer agreed cut off levels for both EtG and FAEEs are for the proximal 3 cm segment of hair. Whilst the testing of 1 cm segments (of the proximal 3 cm segment of hair) might have some value for the purpose of looking at trends (and also at very high levels referred to in (i) above), no cut off levels have been established or generally agreed for 1 cm segments nor, as referred to earlier in this judgment, is there sufficient published data on testing such segments to enable the validity of such tests to be established. Accordingly, any evidence based on the testing of 1 cm segments is unlikely to be sufficient to support conclusions as to the level of alcohol consumption;
(v) Notwithstanding what is set out in the Consensus, the witnesses in these proceedings agreed that, when tests demonstrate levels of EtG and FAEEs above the cut off levels referred to in paragraph 20, the results can be said to be ‘consistent’ with excessive consumption over the relevant period. When a test demonstrates a lower level it is ‘consistent’ with abstinence/social drinking.
(vi) As referred to in (iii) above, the current state of research means that there is no peer agreed cut off level for the line between abstinence and social drinking. In the absence of any such peer reviewed and agreed cut off, any court would, in my view, need specific justification before accepting any such evidence.’
Moylan J
[2010] EWHC 2903 (Fam), (2011) 118 BMLR 65, [2011] Fam Law 131, [2011] 1 FCR 401, [2011] 1 FLR 1345
Bailii
England and Wales
Citing:
Cited – Re F (Children) (DNA Evidence) FD 20-Dec-2007
The court considered the difficulties which can arise from the use of DNA testing in family proceedings. Experts need to bear in mind that their reports should be expressed in terms which can be understood by lay people and in terms which explain . .
Cited – Regina v Weller CACD 4-Mar-2010
The defendant appealed against his convictions for sexual offences, based in part on DNA evidence. He said that the court had not properly applied the rules when considering DNA cases and that there was now additional evidence as to the possibility . .
Lists of cited by and citing cases may be incomplete.
Children, Evidence
Leading Case
Updated: 01 November 2021; Ref: scu.430393