Hair strand testing is a reliable and quick way to test for drug and alcohol use over long periods. Hair tests have helped lawyers gain the advantage in difficult cases, whether to prove innocence or protect a vulnerable victim.
But the success of hair strand testing, like all scientific endeavours, depends on process. It’s not as simple as taking the sample for testing and sending it off for analysis. Legal experts can derive more value through following easy, but critical steps.
Cost shouldn’t be the sole consideration when choosing a laboratory to test a hair sample.
Speed is of greater importance. It won’t be the most affordable service, but speed - combined with the reliability of the testing procedure - can make all the difference in a difficult custody case where time is of the essence.
The speed of the test depends on how advanced the laboratory is. Some laboratories can provide accurate results within 24 to 48 hours of receipt.
The value you gain from the test isn’t only in the result. From the first step to the last, the hair testing process should be clearly defined and followed to the letter. The sample’s integrity cannot be broken at any point during the analysis.
Chain of custody means the test sample is collected, transported and tested in a proper, scientific manner which means each step of the analysis can be traceable and reconstructed at any time. Without a secure chain of custody, a hair sample cannot be used as evidence.
Reliable laboratories will insist that a trained collector or GP collect the hair sample from a donor.
The trained collector will satisfy the conditions demanded by the testing laboratory. Having a professional collect the sample will also help guarantee the chain of custody, ensuring the test results can endure the court’s scrutiny.
To ensure the person being tested is indeed the right person, a reliable witness - usually a lawyer - will be present to guarantee the sampling process’ security.
The lack of trained collectors has led to tragic examples like the Motherisk lab in Canada, where families were torn apart by inadequate sample collection.
The laboratory is an objective entity. The laboratory must have strict and controlled procedures conforming to strict standards and follow international guidelines - but it can only consider the evidence it has in front of it.
Hair testing is a robust, reliable scientific testing when performed by competent laboratories, but it is helpful if the context of the sample is known to the laboratory scientist performing the test.
The donor’s use of medication, for example, must be known. Some types of medication – including codeine – can give the appearance of drug use. Knowing when the medication was taken helps the toxicologist interpret patterns in a donor’s test results.
Laboratories need to know about the condition of each hair sample, too. Factors like hair bleaching or dyeing of the donor’s hair can decrease the amount of drug available in the hair for detection.
Hair strand testing isn’t solely concerned with detecting drug use. It has a more nuanced application, too: it documents changes in use over time, illustrating spikes or declines in use.
Using hair strand testing, we can ascertain whether someone has used over a period of several months.
Hair tests can show an individual has stopped using a drug or alcohol after a set amount of time. The initial test provides a baseline result and subsequent hair testing will show the concentration of substance in the body steadily decreasing, all the way down to 10–15% of the initial concentration.
Hair testing labs must be accredited to minimum standards set by the UKAS (United Kingdom Accreditation Service). The laboratory you choose should, at a minimum, hold an ISO/IEC 17025 accrediation.
This standard addresses laboratories’ competence to use valid sampling and testing methods to produce precise, accurate and reliable results.
Crucially, an ISO/IEC 17025 accreditation does not cover all the types of test a laboratory performs. For hair testing, this means some laboratories may be accredited for testing certain substances but not others.
When a judge orders a hair test, it’s important to ensure the laboratories under consideration are accredited to test for all substances in question. This information can be found on the UKAS website.
The differences in testing and reporting methods used by laboratories cause the accuracy of their results to vary.
The most modern laboratories use liquid chromatography in tandem with mass spectrometry as their primary testing method. This highly reliable process uses a physicochemical test to identify the mass spectrometric fingerprints of substances used by a donor.
The speed of the test is also affected by how advanced the laboratory is. If you need a quick, reliable result, the lab’s testing and reporting processes are of utmost importance.
Hair tests can be used to accurately detect drug or alcohol use after seven days, for up to 12 months. Blood testing can detect immediate drug or alcohol use. Urine and saliva tests detect substance between a half-day and five days after use.
These time factors are crucial and should be considered before the cost of each test method.
These different tests aren’t in competition, however. Hair testing can and should be used with other testing methods. Hair testing offers a longer term picture, and using a secondary testing method provides a full portrait of a donor’s substance abuse.
Some laboratories will conduct hair tests on three millimetre-long hair samples when an allegation of specific allegations are made, like a spiked drink for instance.
This is important if a donor says - for instance - that their drink was tampered with, leading to the presence of a specific drug. This was crucial in a 2013 case where hair strand testing helped acquit a man who stabbed his son after his spiked drink caused him to hallucinate.
Testing a three millimetre section of a hair sample can pinpoint approximately when the substance was ingested - but it can indicate an exceptional instance within a pattern of drug use.
A family lawyer is able to oversee the sampling process to confirm its legitimacy - but once the sample is transported to the lab, the lab will have to ensure the integrity of the sample from the beginning of the analysis to the end when the results are issued.
But family lawyers can also, and should, request a witness statement. A witness statement documents exactly what happened over the course of the test, including when the sample was taken, transported to the lab and analysis within the lab. It also discusses what the results were and what they mean, with an interpretation added to the end.
With hair testing, chasing cost over quality can have dangerous repercussions for family law court outcomes.
Family lawyers should ask and expect more from their testing partner – and be prepared to push back when the service they receive isn’t what they expected.