It is now 12 years since LB Richmond v B & W  EWCA 2903 (fam), the first case involving a challenge to alcohol hair strand test results. Mr Justice Moylan gave guidance which remains good law to date in the event that a client (or opponent) disputes the results of hair strand testing; however, there are some updates to testing procedures that practitioners need to be aware of since that case.
The Society of Hair Strand Testing (SOHT) last updated its Consensus For The Use Of Alcohol Markers In Hair (the Consensus) in 2019. The Consensus represents the agreement of 18 experts and is ratified by the General Assembly of the SOHT.
The 2019 consensus states that a negative EtG result in pubic hair could be used to demonstrate abstinence and either an EtG or EtPa test in head or body hair can demonstrate chronic excessive alcohol consumption. EtPa is one of four Fatty Acid Ethyl Esters (FAEE), often all four are tested but the EtPa marker is considered the most sensitive.
The consensus departs from the legal position set out by Mr Justice Moylan who was clear that the use of both EtG and FAEE hair strand tests helps to cancel out the incidence of false negatives and false positives that occur with both types of hair strand test.
The case law recommends that in order to provide the most complete evidential picture other testing should also be employed. The court usually requests a blood test alongside the hair strand tests. A PEth test is considered the most sensitive blood test as it tests a direct biomarker of alcohol. Testing for CDT and Gamma GT in the blood is the other option that is often recommended. The test companies often offer a package of two hair strand tests and a blood test at a slightly cheaper rate than requesting three separate tests. Ordering the full package of tests at the outset avoids further tests having to be obtained in the event the client challenges the result. It is essential that a report analysing and providing an expert opinion on the meaning of the results is requested.
Hair strand testing companies are expert witnesses to the court and subject to the duties of any expert in family proceedings. If the results of testing are challenged by any party, written questions should be put to the expert in the first instance. The company should be provided with any other test results the client has previously undertaken. They may have had breathalyser or urine testing undertaken by a substance misuse service. In certain cases, it may be necessary to instruct an independent toxicologist to provide an opinion on disputed results.
The barristers at Garden Court Chambers are able to provide further advice on the legal issues that arise in relation to disputed test results.