High Court confirms reliability of hair strand testing

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High Court

Hair testing for cocaine and other common drugs of abuse is regularly used in child and family law cases across to the world to allow courts to establish a change in drug abuse patterns. However there exists some confusion as to what the testing offers and what its limitations are. 

DNA Legal, along with two other leading testing firms, were asked by The Honourable Mr Justice Peter Jackson to intervene in the case of Re H.  Together we were able to help the Court understand both the science behind the testing, if and why differences between testing company results exist and what can be done to present results in the most accessible way.

The case in question revolved around whether a mother had taken cocaine or been passively exposed to cocaine after claiming she had stopped taking the drug a year or so earlier.  It considered the reliability of testing for cocaine where results are in the ‘low range’, and where contamination, for example through social contact with users, may have been an issue.

Since its foundation, DNA Legal has focused on bringing cutting edge DNA and drug testing to the legal profession while presenting this throughout simple to read ‘expert reports’. Managing Director, David Nicholson, has conducted over 400 training events, lectures and CPD’s across the UK.  From this it’s clear that both the level of understanding how testing works, and the way testing is used across the country varies significantly. 

In  ‘Re H: Hair Strand Testing’ – 29th September 2017, the Court reaffirmed the role that hair strand testing for cocaine has to play in family courts.   In his judgement, Jackson J quoted Bristol City Council v The Mother and others [2012] EWHC 2548 (Fam) (amongst other cases), and commented that it had been helpful to him in forming his judgement:

            “(1) The science involved in hair strand testing for drug use is now well-established and not controversial.

            (2) A positive identification of a drug at a quantity above the cut-off level is reliable as evidence[1] that the donor has been exposed to the drug in question.

           (3) Sequential testing of sections is a good guide to the pattern of use revealed.

          (4) The quantity of drug in any given section is not proof of the quantity actually used in that period but is a good guide to the relative level of use (low, medium, high) over time.”

                    [1]PJ: evidence, not proof.

The case also makes it very clear that testing can distinguish between use and contamination where appropriate protocols are in place, although of course test results are only part of the evidence that must be properly weighed and considered by each court.

DNA Legal has always been very clear that drug test reports are part of the ‘picture’ when considering whether or not someone has consumed drugs or changed their pattern of use, and also that the value of a test lies as much in the careful analysis by the person who interprets results (in this case, Dr. Salah E. Breidi) as it does in the raw data that the test itself provides, and this is consistent throughout the judgement in Re H. 

We see the judgement in this case bringing a helpful level of transparency to the industry. DNA Legal’s approach and processes, particularly its cut off levels and policy for always analysing the washes stand up well in light of this transparency. We have long held that people whose hair is being tested, and those who look to us to provide the most accurate test results possible deserve the most precision and detail.

Jackson J included in his judgement (at Paragraph 59), includes a list of suggestions for testing firms to consider and advises:

The reader must take care to understand what is being read, and not jump to a conclusion about drug or alcohol use without understanding the significance of the data and its place in the overall evidence.

The purpose of the overall case was first and foremost on how to support the mother to identify if she has changed her drug abuse patterns or whether she continued to abuse drugs.

The result of the judgement carried serious consequences for her and her child. By three leading testing companies stepping in to support the court it has enabled a far greater level of understanding from the court and provided a basis on which the Honourable Mr Justice Peter Jackson was able to reach his judgement both on the way testing was conducted and on the future of the child and her relationship with their biological parents.

Untimely it will be up to the participant if they choose to lead a drug free life, but with greater clarity on how cocaine hair strand test results can be reported it should help all parties involved be able to understand and use the evidence provided by fully accredited testing firms.

It is not for the court hearing one case to dictate the way reports are written by those who have intervened in this case or by others who have not taken part, but I include the following seven suggestions in case they are helpful.

(1)       Use of high/medium/low descriptor:

This is in my view useful, provided it is accompanied by:

  • A numerical description of the boundaries between high/medium/low, with an explanation of the manner in which the boundaries are set should be stated.
  • A clear statement that the description is of the level of substance found and not of the level of use, though there may a broad correlation.
  • A reminder that the finding from the test must always be set alongside other sources of information, particularly where the results are in the low range.

(2)       Reporting of data below the cut-off range:

There is currently inconsistency as between organisations on reporting substances detected between the lower limit of detection (LLoD) and the lower limit of quantification (LLoQ), and those between the LLoQ and the cut-off point.

I would suggest that reports record all findings, so that:

  • A finding below the LLoQ is described as “detected, but so low that it is not quantifiable”
  • A result falling below the cut-off level is given in numerical form

and that this data is accompanied by a clear explanation of the reason for the cut-off point and the need for particular caution in relation to data that falls below it. 

(3)       Terminology

Efforts to understand the significance of tests are hampered by the lack of a common vocabulary to describe results in the very low ranges, Descriptions such as “positive”, “negative”, “indicates that” and “not detected” can be used and understood vaguely or incorrectly.  The creation of a common vocabulary across the industry could only be achieved by a body such as the SoHT.  In the absence of uniformity, reporters should define their terms precisely so that they can be accurately understood.

(4)       Expressions of probability:

The Family Court works on the civil standard of proof, namely the balance of probabilities.  It would therefore help if opinions about testing results could be expressed in that way.  For example:

“Taken in isolation, these findings are in my opinion more likely than not to indicate ingestion of [drug].”

“Taken in isolation, these findings are in my opinion more likely than not to indicate that [drug] has not been ingested because….”

“Taken in isolation, these findings are in my opinion more likely to indicate exposure to [drug] than ingestion.”

(5)       Where there is reason to believe that environmental contamination may be an issue, this should be fully described, together with an analysis of any factors that may help the reader to distinguish between the possibilities.

(6)       The FAQ sheet accompanying the report (which might better be described as “Essential Information”), might be tailored to give information relevant to the particular report, and thereby make it easier to assimilate.

(7)     When it is known that testing has been carried out by more than one organisation, the report should explain that the findings may be variable as between organisations.

We will be exploring in depth what the judgement means in practical terms over the coming months, if you are interested in attending a Free of Charge Conditional Professional Development training event please contacts us at cpd@dnalegal.com.​

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