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Hair Strand Testing for Cocaine

Emily James and Kate Tompkins, barristers of 36 Family, consider a new judgment in which Sir Peter Jackson affirmed, and offered guidance on, current testing arrangements.

Emily James, barrister, 36 Family

Kate Tompkins, barrister, 36 Family









Emily James and Kate Tompkins, barristers, 36 Family


Peter Jackson J (as he then was) handed down judgment in H (A Child : Hair Strand Testing) [2017] EWFC 64 on 29th September 2017, a test case in respect of the validity of hair strand testing in light of multiple criticisms made by a jointly-instructed trichologist, with potentially far-reaching consequences in this and many other cases.

This judgment provides long awaited guidance to those within the family justice system utilising hair strand testing for cocaine and welcome affirmation to the providers of the tests themselves. 

The key distinction between hair strand testing for cocaine and hair strand testing for cannabis is that there is no definitive metabolite for cocaine. In tests for cannabis the presence of the metabolite THC-COOH is said to be evidence of use, with cocaine there are a number of metabolites and the presence of one or other to a greater or lesser degree requires careful analysis and explanation in order to determine what evidential value the hair strand test has.

In the judgment Peter Jackson J calls both on testing laboratories to make sure that as far as possible the true significance of the data is explained, and on practitioners to ensure competence in their understanding of the methodology of hair strand testing so that the significance of the data and its place in the overall canvas of the evidence is understood. 

Peter Jackson J also questioned whether, in retrospect, the evidence of 'ostensibly positive' hair strand test results supporting very low level or infrequent drug use at interim removal stage was in truth sufficient to justify the removal of a baby at birth when balanced against the other evidence supporting no use. The judgment is therefore  of major significance to all of us practising in this area of family law.

The proceedings concerned a baby girl who was 8 months old by the time of the final hearing. She was removed from her mother at birth but returned to her care at the age of six weeks under supervision and since July this year lived with her mother at home. 

The mother had a long history of drug abuse and by the age of 21 was regularly using heroin and crack cocaine.  This case related to the fourth child of the mother, who is now in her early 30s. The three older children had been removed from her care, the oldest placed with her maternal grandmother under a Special Guardianship Order in 2012, the two subsequent children placed together for adoption in October 2016, care and placement orders having been made in respect of them in July 2016.

Pending the outcome of these proceedings the adoption proceedings in respect of the two middle children were stayed given the ramifications of any findings that the validity of hair strand testing might have on the orders made.

By the time the matter came to final hearing the issues were relatively narrow but had not always been so. The child had been removed at birth because of an 'ostensibly positive' hair strand test result which, set against the background history, led the local authority to argue that she would not be safe in her mother's care.

Even after she was returned home, the local authority's final case was that she should be removed again and placed for adoption: this plan changed only two days before the hearing began.

By the time of the final hearing it was agreed that although the threshold for intervention was crossed on the basis of the past history and future risk the child would remain in her mother's care with support provided by the local authority, by other agencies and by her father and maternal grandmother.  The only legal issue was whether the arrangement should be underpinned by a care order or a supervision order.

The issues
The hearing involved five days of evidence because of the underlying factual issue: whether the mother had been using drugs, albeit at a low level, during the past two years.   She adamantly denied doing so and, with one significant exception, the other evidence supported her. 

The exception was the body of scientific information from hair strand tests taken over the two-year period, interpreted by the testing organisations as showing low-level cocaine use for at least some of the time.  That was challenged by the mother. The court heard from five expert witnesses: one from each of three testing organisations, one on behalf of the mother, Dr  Hugh Rushton, a trichologist, and one jointly instructed, Dr Andrew McKinnnon, forensic toxicologist. 

The local authority argued that the hair strand testing showed that complete abstinence had not been achieved which raised the level of risk that the child would get caught up in future drug use of the kind seen in the past. It was also argued that the hair strand testing showed that the mother had not been telling the truth and consequently she could not be fully trusted.

The mother's case was that she had not used drugs since July 2015, something she had maintained in the earlier proceedings relating to her two older boys.

The difficulties in interpreting results accurately from reports in their current form caused Peter Jackson J to include in his judgment guidance intended to improve the way in which such evidence is presented and understood.

At an early case management stage the mother sought and was granted permission to instruct a trichologist. Dr Rushton's first report raised questions as to the validity of the hair strand testing process and further expert opinion was sought from Dr McKinnon, a forensic toxicologist jointly instructed by the parties.  Dr McKinnon agreed to some degree with concerns raised by Dr Rushton as to risks associated with external contamination and the nature and significance of industry guidelines.  Both Dr Rushton and Dr McKinnnon identified the need for analysis of the hair 'washings' to measure external contaminants before being able to establish if cocaine and/or metabolites within the hair itself could be said to indicate use.

Peter Jackson J identified the topics in issue as including:

(1) The significance, if any, of the variability of the results as between the different laboratories. 

(2) The nature and significance of industry guidelines.

(3) The significance of findings of cocaine or its metabolites below cut-off levels.

(4) The significance of the comparison between wash samples and test samples.

The judgment concludes that the variability of findings from hair strand testing does not call in to question the underlying science but underlines the need to treat numerical data with proper caution.

Peter Jackson J accepted that Dr Rushton had asked some good questions and had done so fearlessly but for the most part was unable to accept the answers he gave. All in all the judge did not consider Dr Rushton's criticisms of hair testing science, or of the activities of the companies concerned in this case, were made out to any significant extent.

Much of the debate between the experts centered around industry guidelines as to the necessary requirements to establish a positive hair strand test.

The cut off levels are described as safety mechanisms which Dr Rushton and Dr McKinnon insisted be strictly adhered to. The hair strand test providers suggested that readings below cut off levels could still be informative and should not be disregarded.

Peter Jackson J found that Dr Rushton, when giving evidence, required more from the hair strand testing process than it could be expected to provide.  He did not recognise Dr Rushton's description of 'agreed international guidelines', concluding that the current industry standard in this country is found in the guidelines issued by the SoHT (Society of Hair strand Testing).  

The court noted that Dr Rushton's long experience in trichology did not significantly extend in to toxicology. Jackson J found that Dr Rushton's insistence on his point of view overlooked many of the realities that allowed science to grapple with everyday problems.

It was noted by the judge that, in contrast, Dr McKinnon was a notably cautious witness but to the extent that he was able to express an opinion his evidence could be depended upon.

His Lordship noted the evidence of the interveners to be evidence-based and carefully considered and that they have a combination of expertise and experience that enabled them to deal satisfactorily with the issues under consideration.

There are currently nine accredited hair strand testing organisations working in the family law arena. Peter Jackson J, whilst not suggesting it is for the court hearing one case to dictate the way reports are written, does include suggestions under the heading 'Report writing and reading' (paras 57 to 59), 'in case they are helpful'. The suggestions are essential reading for those in the family justice system seeking to interpret the results of hair strand testing.  Further, it is not unreasonable to expect providers of hair strand testing to adopt the court's suggestions given that a consequence of failing to do so may be that their market share could reduce if they are not deemed to be of a standard sufficient to assist the court, or indeed if their value can be undermined by assiduous analysis.

Care planning and burden of proof
It was accepted within these proceedings that the mother had turned her life around to the point that she was now capable of looking after one child with support.

Unfortunately the local authority's care planning was described in this case as 'sub-optimal' with a high turnover of social workers and poor consultation.  Ultimately, despite positive findings that the mother had indeed used cocaine during 2016 and lied about it, the court made a supervision order rather than the care order sought by the local authority. Peter Jackson J observed that a supervision order may, in the particular circumstances of this case, avoid the possibility of some 'unintended disadvantages from the local authority sharing parental responsibility'.

This case also reminds practitioners that presence of an ostensibly positive hair strand test does not reverse the burden of proof and the local authority is required to prove its case. Although in this case Jackson J made findings that the mother had used cocaine, albeit at a relatively low and infrequent level during the latter part of 2015 and during 2016 and that she had not told the truth about it, he was not satisfied that the local authority had proved its case in respect of alleged use in 2017.

In the context of making those findings the court reminded those of us in the family justice system that any assessment of a family situation by the court or other professionals involves the gathering and analysis of a range of information.  Most of the information is factual, and in some cases it will be interpreted by experts, who will express an opinion.  That will be the case when scientific investigations such as hair strand tests are carried out.  These tests can provide important information, but in order for that to be of real use, the expert must (a) describe the process, (b) record the results, and (c) explain their possible significance, all in a way that can be clearly understood by those likely to rely on the information.  If these important requirements are not met, there is a risk that the results will acquire a pseudo-certainty, particularly because (unlike most other forms of information in this field) they appear as numbers.

Emily James and Kate Tompkins, both from 36 Family, appeared in the case led by William Tyler QC and Hannah Markham QC, both also from 36 Family.