Mr Justice Baker has given judgment in a case concerning the reliability of hair strand drug testing.

In the care case of Bristol City Council v A and A and SB and CB and Concateno and Trimega (interveners) [2012] EWHC 2548 (Fam), the mother underwent a hair strand drug test carried out by Trimega in June 2011. The results showed an increasing use of cocaine and opiates up until the date the sample was taken. The mother strongly denied such drug use and was given permission to take a second test which was carried out by Concateno. This test supported her version of events that she had not taken drugs in the previous four months.

The two drug testing companies were given permission to intervene in the proceedings and a significant amount of time and effort was spent preparing for the hearing. However, shortly before the hearing, Trimega conceded that its analysis was erroneous and unreliable, probably due to a human error in the collection process. The precise error was unclear but the court accepted that the mother had been abstinent from drugs for the four months leading up to the hearing and ordered a community based assessment.

In a further hearing, the court considered the following questions:

“What general guidance, if any, should be given to family courts about the use and interpretation of, and reliance upon, hair testing in the light of the apparent inconsistencies in the testing results provided by the two companies? Does hair testing remain a reliable method for determining drug use in family courts?”

Counsel for Concatena argued that “Trimega’s inadequacies risked belittling and damaging the reputation of this important testing and the companies carrying it out” and invited the court to accept four general propositions about the use of hair strand testing as follows:

  1. The science 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 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.

He also asked the court to provide more specific guidance for labs carrying out hair strand tests in the interests of the family justice system.

Counsel for Trimega accepted the general propositions but argued that Concatena’s primary motivation was to obtain judgment which was critical of Trimega and guidance from the court that could be used to commercial advantage. He stated that “the issue in the proceedings that fell to be resolved for their determination, warranting the involvement of the interveners, has long since been resolved. The focus of the court must now properly and exclusively be on the subject children. This is a care case. It is not some public enquiry.”

The judge endorsed the four general propositions about the use of hair strand testing but declined to offer any more detailed guidance. The judge held that care proceedings were not the appropriate forum for such an enquiry and it would not be appropriate or proportionate to direct the court’s limited resources to such a general inquiry. He concluded by emphasising that in certain circumstances the family justice system does require expert drug testing evidence and that erroneous evidence can lead to grave miscarriages of justice.