Biochemist Expert Witness

Introduction

A biochemist expert witness applies specialist knowledge of chemistry, biology and laboratory science to evidence arising in legal proceedings. Their expertise may be relevant where cases involve laboratory results, drugs, metabolites, toxins, hormones, proteins, enzymes or other biochemical substances.

Experts in this field may have backgrounds in clinical biochemistry, analytical biochemistry, toxicology or pharmaceutical science. Qualifications can include a BSc, MSc or PhD in biochemistry or a related discipline, HCPC registration as a Clinical Scientist and Fellowship of the Royal College of Pathologists. The precise expert selected should have experience directly relevant to the scientific questions in the case.

Biochemists will commonly undertake a desktop assessment, reviewing laboratory and documentary evidence rather than physically examining an individual.

Typical Case Types

Criminal Court

A biochemist may assist in criminal proceedings involving drugs, alcohol, poisons, toxic substances or disputed laboratory evidence. Instructions may involve interpreting blood or urine results, reviewing toxicology findings or considering whether laboratory methodology supports conclusions advanced by the prosecution or defence.

Relevant issues can include therapeutic versus toxic drug concentrations, metabolites, novel psychoactive substances, suspected poisoning, toxic alcohols and analytical techniques such as LC-MS/MS, GC-MS and immunoassay.

The expert may also examine sample integrity, analytical interference, detection limits, calibration, quality control and chain of custody.

Criminal expert evidence must comply with Criminal Procedure Rules Part 19 and, where applicable, the requirements of the Forensic Science Regulator.

Family Court

In family proceedings, biochemical evidence may be relevant to drug and alcohol testing, medication, toxic exposure, metabolic abnormalities, prenatal or neonatal drug exposure, or allegations involving poisoning or fabricated or induced illness.

The expert may be asked whether laboratory results support a proposed medical explanation, whether medication could account for an abnormal result or whether conclusions drawn from testing are scientifically justified.

Expert evidence in family proceedings is governed by Family Procedure Rules Part 25. The expert’s overriding duty is to assist the court independently.

Coroners’ Courts

Biochemists may assist coroners where laboratory or toxicological evidence is relevant to how a person came by their death. This may include suspected overdose, poisoning, drug interactions, therapeutic drug monitoring, metabolic abnormalities or interpretation of laboratory results preceding death.

Post-mortem toxicology may require consideration of sample location, decomposition, redistribution and specimen integrity.

Role of the Expert Witness

The biochemist’s role is to explain the scientific significance and limitations of laboratory evidence. This can include consideration of:

• analytical methodology and reliability;
• metabolites and pharmacokinetics;
• sensitivity and specificity;
• limits of detection and quantification;
• measurement uncertainty;
• cross-reactivity and interference;
• sample collection and storage; and
• alternative explanations for abnormal findings.

The expert must distinguish between association, compatibility and causation and should not express opinions outside their area of competence.

Under CPR Part 35, where applicable, the expert’s duty is to assist the court and overrides any obligation to the party instructing or paying them.

Evidence and Reporting

Relevant records may include laboratory reports, toxicology results, clinical records, medication charts, post-mortem reports, sample collection information, laboratory methodology, quality-control records and other expert reports.

A typical report will identify the expert’s qualifications, instructions, documents reviewed, methodology, relevant scientific findings, interpretation, alternative explanations, limitations and conclusions.

Biochemists may also provide addendum reports, respond to written questions, participate in expert discussions and joint statements, and give oral evidence where required.