Hair strand test analysis – is it reliable?

In the recent case of H (A Child: Hair Strand Testing) [2017] EWFC 64, Mr Justice Peter Jackson upheld the existing practices of providers of hair strand tests for cocaine, but has moved to offer suggestions as to how their reports might be written in the future, in order to assist the family courts and parties in proceedings.

In this case, the court was challenged by the evidence of “…an ostensibly positive hair strand test…” appearing to show very low level or infrequent cocaine use and whether, in light of other urine tests demonstrating no use of cocaine, it was justifiable to remove a baby at birth.

The key factual dispute before the court was the mother’s use of cocaine. The child’s mother has been subjected to numerous urine and hair strand tests over a two-year period. In assessing the hair strand test results, illustrating low level and/or infrequent cocaine use, the court heard from several witnesses from the leading testing organisations. Their general consensus suggested that the positive hair strand results were likely to stem from the active use of cocaine, rather than from external contamination or environmental factors – although this finding was not unanimous.

The judgment from Mr Justice Peter Jackson concluded that the variability of findings from hair strand testing does not call in to question the underlying science of the testing procedure, but does underline the need to treat numerical data with proper caution. When considering the writing of hair strand test reports, Mr Justice Peter Jackson stated that the report author “… must make sure as far as possible that the true significance of the data is explained in a way that reduces the risk of it becoming lost in translation. 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…”

Furthermore, Mr Justice Peter Jackson’s suggested moving forward, reports should include:

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

(2) Reporting of data below the cut-off range, e.g. “detected, but so low that it is not quantifiable” with a result falling below the cut-off level given in numerical form.

(3) The creation of a common vocabulary and terminology across the industry could only be achieved by 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 – i.e is something more likely than not.  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  cocaine.”

“Taken in isolation, these findings are in my opinion more likely to indicate exposure to cocaine 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 test reader to distinguish between the possibilities.

If you would like to discuss issues relating to hair strand analysis, testing or concerns regarding your children following the breakdown of your relationship, contact one of our expert solicitors today on 01234 88977 or 0207 177 9777 for a free consultation. Serving Bedford and London, our lawyers can help you with your family law  matters.

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