Jurors ‘should be told’ how much expert witnesses are paid, MPs told

Former trader Tom Hayes tells MPs juries must know expert witnesses’ pay and track record

Juries should be informed how much expert witnesses are paid and how frequently they have appeared for either side in a trial, MPs have been told during a discussion on the use of expert evidence in the criminal justice system.

The proposal was raised by Tom Hayes, the former City trader whose conviction in the LIBOR rate-rigging case was quashed by the Supreme Court earlier this year. Hayes made the remarks at an event convened by the All-Party Parliamentary Group on Miscarriages of Justice, where a panel chaired by Lord Garnier KC, the former solicitor general, examined the role of expert evidence in ensuring fairness in trials.

Hayes told MPs that there was “a complete inequality of arms” between the prosecution and defence when it came to expert evidence, referring to his own case as an example. During his original trial, Hayes said, the prosecution called two expert witnesses—one of whom, he claimed, gave “extremely damning testimony”—while he was unable to call any experts in his defence.

“In my opinion, one thing that should be disclosed to the jury, and I don’t think I’ve ever heard anyone actually recommend this, is how often an expert has been instructed by both sides,” Hayes said. “So if an expert has been instructed 30 times by the prosecution, then the jury should know that. The jury should also know how much they have been paid. As a juror, I would think that someone who gave evidence for both sides equally would probably be more credible than someone who gave evidence solely for the CPS.”

Hayes’s comments came amid renewed public and parliamentary scrutiny of the role and reliability of expert witnesses in the justice system following the Post Office Horizon scandal and the conviction of nurse Lucy Letby. The discussion also coincided with a series of parliamentary reviews into how scientific evidence is presented and tested in criminal proceedings.

Professor Carole McCartney, who teaches law and criminal justice at the University of Leicester, told MPs that forensic scientists and other expert witnesses are held to strict professional standards and can face significant consequences for errors. “If they are seen to be making errors or there is criticism of their judgement, they are reported to the regulator. They are heavily regulated and do suffer consequences if they make mistakes,” she said.

Earlier this year, the Westminster Commission on Forensic Science published a report containing 34 recommendations to improve the quality and consistency of forensic evidence in criminal trials. Among its proposals were measures to make expert witnesses nationally available to both prosecution and defence teams and to improve the communication of scientific concepts to juries.

At the same event, Stephanie Davies, a former senior coroner’s officer and death scene investigator, said that an inquisitorial approach to trials could help address weaknesses in how evidence is tested. She suggested that a system focused on establishing facts through judicial inquiry, rather than adversarial argument, might reduce the risk of miscarriages of justice.

Concerns over the use of expert testimony are not new. In 2011, the Law Commission published a report recommending a new admissibility test for expert evidence, additional judicial guidance, and a formal framework for screening evidence before it is presented in court. However, two years later, the Ministry of Justice confirmed it did not intend to implement most of those recommendations.

The call for transparency about expert witnesses’ payments and their record of courtroom appearances reflects a broader debate about fairness and balance in the criminal justice system, particularly when cases hinge on highly technical or scientific evidence that can strongly influence juries.