Are hair strand tests reliable enough for Family Court decisions?

Every year, the future of hundreds of families is influenced by hair strand tests. The results can determine whether a child goes into care or stays with their parents or guardians.

Hair strand tests have been used for decades by Family Courts to check for drug or excessive alcohol use when making decisions about child welfare. However, a number of recent cases have sparked concerns about how test results are presented and interpreted.

In this blog, our Family Law specialists explain the role of hair strand tests and what to do if you believe your results are inaccurate.

How do hair strand tests work?

When a substance passes into the bloodstream, it often leaves a trace in a person’s hair. As the hair grows, this trace remains and can be used to show drug and alcohol consumption over several weeks or even months. This is different to blood and urine tests, which can only provide a snapshot view for the last few days. 

As well as identifying the use of illegal drugs, such as ecstasy and cocaine, hair strand tests can reveal potential misuse of prescription medication, including painkillers and sedatives. The majority of test results are presented as either positive or negative based on industry standard cut-off levels.  

How are hair strand tests used in family law?

Hair strand tests are often reviewed by judges when deciding if it’s safe for children to live with their parents or guardians – especially when there’s a suspicion of drug or alcohol misuse. For example, if a mother with a history of heroin addiction applies to a local authority to have their child returned to their care, social workers need to check they are no longer using drugs. 

Experts have recommended that judges view hair strand tests alongside other contextual evidence. This, however, doesn’t always happen, which means results can be presented at a hearing without independent expert witness interpretation. Critics say this can lead to miscarriages of justice. For example, in 2024, the Court of Appeal overturned a decision to take three children away from their family based on hair strand tests.

Are hair strand tests accurate?

Although hair strand science is sound, there are growing concerns that test results could be impacted by other factors. Hair types, beauty products and even environmental conditions can all influence whether someone tests negative or positive for certain substances. Testing processes also often vary between labs, which means the same sample can return completely different results.

The Family Justice Council has set up a working group in response to the criticisms and is expected to issue best practice guidance at some point in 2026. It’s hoped this will increase awareness of the variables than can impact the interpretation of test results.

Can you challenge hair strand test results?

Seeking legal advice prior to a Family Court hearing is critical – especially if you disagree with the findings of a hair strand test. If a judge automatically accepts the results without further qualification or consideration, it could impact your family for years to come.

When representing families in child welfare cases, we combine test results with other evidence to provide a broader picture of home life. Where appropriate, we also request expert opinion on test findings and processes to validate the accuracy of a report.

If you need advice on a hair strand test or a Family Court hearing, our specialist lawyers are here to help. We understand how distressing and life-changing these proceedings can be for you and your loved ones. Contact our Family Law team on enquiries@attwaters.co.uk or 0330 221 8855 to find out how we can support you.