Ensuring Reliability and Independence in Expert Testimony

In a recent article in The Guardian, Patrick Hodge, Deputy President of the Supreme Court and President of the Expert Witness Institute, urged judges and lawyers to remain “on their guard” when assessing expert witness evidence, highlighting that as legal cases grow increasingly complex, reliance on expert testimony has never been greater.

“I think the nature of modern technology and the nature of modern medical science makes these things much more expert-driven than they were,” Hodge said. “But you can’t be in thrall to an expert witness; you have to approach their evidence with care.”

This warning comes at a time of heightened public scrutiny over expert testimony. Lawyers appealing the conviction of neonatal nurse Lucy Letby argue that expert evidence played a key role in her trial, reigniting discussion about how experts are selected and assessed.

The Importance of Scientific and Technical Literacy

Hodge emphasised that judges and lawyers need to improve their “scientific and technical literacy” to prevent miscarriages of justice. He explained:

“As a judge, you need to be on your guard and make sure that you feel they are in a position to be properly expressing opinions on that subject. To say: ‘Does your experience justify you expressing an opinion on that matter?’”

Senior legal and scientific figures have highlighted that judges may encounter highly specialised scientific evidence without prior training in that area. Resources from organisations like the Royal Society, which provide seminars and primers on subjects from DNA analysis to statistics, are increasingly valuable for supporting informed judicial decision-making.

Lessons from Previous Civil Cases

There are several civil cases that underscore the importance of clear, reliable, and professionally presented testimony.

• Liverpool City Council v Ms A & Ors: A clinical psychologist’s report was deemed unreliable, prompting the court to instruct a replacement expert. The original expert requested anonymity, but the judge emphasised transparency and accountability where professional standards are not met.
  
• Arksey v Cambridge University Hospitals NHS Foundation Trust: The High Court found that the claimant’s expert evidence fell far below the standard expected of a competent expert witness, with unprofessional conduct noted during proceedings.
  
• Palmer v Mantas & Liverpool Victoria Insurance: An expert altered their report at the behest of the instructing solicitor, subsequently lied about the changes, and then amended the statement again. This misconduct resulted in a suspended prison sentence, highlighting the serious consequences of breaching professional duties.

Hodge also highlighted broader concerns:

• Experts may inadvertently compromise impartiality by focusing on pleasing instructing lawyers or parties.
  
• Some individuals claim expertise in areas with limited scientific basis, requiring careful judicial scrutiny.
  
• Repeated use as an expert can lead to a “protect the doctor” mentality, where defending evidence overtakes explaining it.
  

Supporting Expert Witness Practice

Organisations such as the Expert Witness Institute and Bond Solon provide training, accreditation, and ethical guidance to help experts maintain independence, uphold professional standards, and deliver reliable testimony. Hodge notes that bodies such as these are essential in supporting experts to explain their evidence clearly rather than simply defend it.

Heightened scrutiny of expert evidence should be viewed as a constructive safeguard rather than a criticism. Through accreditation, training, and reflective practice, expert witnesses can continue to provide reliable, impartial, and authoritative testimony, reinforcing both judicial decision-making and public confidence.

Governance of Expert Evidence

Expert witnesses in the UK are governed through two main procedural frameworks.

In civil proceedings, the Civil Procedure Rules (CPR) Part 35 set out the duties of independence, transparency, and the overriding obligation to assist the court rather than the instructing party.

In criminal cases, the Criminal Procedure Rules (CrimPR) Part 19 provide parallel requirements, ensuring that expert testimony is objective, unbiased, and properly presented. Recent amendments to Part 19 of the Criminal Procedure Rules 2020, effective 16 August 2025, further strengthen governance around expert evidence:

• Expert Evidence within Fact Evidence: Courts can now explicitly apply expert rules to evidence introduced as fact, ensuring proper evaluation of embedded expert opinion.
  
• Court’s Discretion: Judges have clearer powers to apply expert evidence rules to mixed evidence, supporting rigorous scrutiny.
  
• Duty to the Court (Rule 19.2): Experts must provide objective, unbiased opinions and actively assist the court in case management.
  
• Content of Expert Reports (Rule 19.4): Reports must include a declaration of truth, aligning with witness statement standards.
  
• Time Limits: Deadlines are now expressed in business days, reducing confusion and streamlining proceedings.
  

These updates highlight the importance of experts being not only clinically and technically competent but also fully aware of legal procedures.

Ensuring Excellence in Expert Witness Practice

At McCollum Consultants, we are committed to supporting the highest standards of expert testimony. Our experts undergo rigorous medico-legal training, appraisal, and continuous professional development (CPD), ensuring they remain at the forefront of Medical Expertise and Legal Understanding. We also provide tailored training for legal and law enforcement professionals, helping them interpret complex medical evidence and work effectively with expert witnesses.

By combining Medical Expertise and Legal Understanding with independence and professionalism, McCollum Consultants ensures that every expert witness we provide is reliable and fully prepared to contribute to fair and effective justice.

For enquiries or to engage our experts, contact us at:

Tel: +44 (0)161 218 0223
Email: info@exp-w.com