What is expert witness evidence?

Expert witness evidence is not needed in all legal proceedings but it plays an important part in many cases. Instructing an expert witness is not unusual—there are many much-publicised cases where the role of expert evidence has been significant. The involvement of expert witnesses in famous expert witness cases often leads to changes in how expert evidence is formulated and the effect it may have on the outcome of the proceedings.

Why are expert witnesses instructed?

Medicolegal court reports are requested where expert witness evidence is required. Renowned Expert witnesses include doctors, psychologists, psychiatrists, social workers, and other professionals who are instructed to give expert opinions in legal proceedings. Expert witnesses are often instructed in cases where expert evidence is necessary to enable the court to understand specific issues, such as capacity, intent, causation etc.  Expert evidence may be important in determining the right outcome. For example, in cases where a mental disorder is an issue, the evidence of a psychiatrist may influence the conduct of legal proceedings, it may help to adduce medical evidence relevant to trial and may be the deciding factor between imprisonment and mental health treatment.  There have been many famous expert witness cases.

John Worboys: almost released after numerous sexual offences

John Worboys worked as a cab driver and was charged with sexually assaulting several of his female passengers. John Worboys’s victims alleged that he assaulted them after offering them champagne which he had spiked with drugs. His offences led to him being named “the black cab rapist” by the UK press. In 2009, he was charged with assaulting 12 women. After his conviction at Croydon Crown Court, several more women made allegations of sexual assault against him.

John Worboys was given an indeterminate prison sentence. As with all indeterminate sentences, decisions around release are the sole responsibility of the Parole Board.  It is not uncommon for the Parole Board to instruct expert evidence from psychiatrists and psychologists.  Therefore, when John Warboys applied for parole, an independent psychologist was instructed by his legal representative to assess his risk. Having served 10 years in prison, the psychologist recommended his release from prison.

This opinion differed from the opinions formed by the other professionals, who concluded that John Worboys should remain in prison. The parole board initially approved him for release. This decision attracted intense media attention and was seen to be a controversial decision due to the nature and severity of his offences.  Following criticism of the decision, the high court ordered the parole board to re-examine Worboys’ case. Today, he remains in prison. While his potential release faced intense scrutiny, it demonstrates how influential an expert witness report can be.

Sally Challen: murder reduced to manslaughter

In 2011, Sally Challen was convicted of murdering her husband before Guildford Crown Court. Sally Challen claimed she experienced years of emotional abuse before killing him with a hammer. She was sentenced to life in prison.  After she had spent several years in prison, an independent consultant psychiatrist was instructed as an expert witness. The psychiatrist formed an opinion of her mental state at the time of the homicide. The psychiatrist found that she had an adjustment disorder at the time she killed her husband, enabling her solicitors to challenge her conviction for murder. Although she was due to face further trial at the Central Criminal Court, on the basis of the expert evidence, the Crown accepted her plea to the lesser offence of manslaughter on the grounds of diminished responsibility.

Because she had already served nine years and four months of her initial life sentence, she was released following the change of conviction. Sally Challen’s appeal demonstrated the importance of expert evidence in establishing the correct outcome for a mentally disordered offender.

Sally Clark: “one of the great miscarriages of justice in modern British legal history”

In 1999, Sally Clark, a solicitor, was convicted of murdering her two infant sons (one in 1996 and the other in 1998) at Chester Crown Court.  Her defence had argued that the children had died of Sudden Infant Death Syndrome (SIDS), but expert witness, Sir Professor Roy Meadow, told the court that the probability of two children from an affluent family suffering SIDS was 1 in 73 million.  She unsuccessfully appealed against her conviction in 2000.  However, Solicitor, Marilyn Stowe, had concerns about the expert evidence of Professor Meadow. She questioned the statistical basis of Professor Meadow’s evidence, which had led to Sally Clark being sentenced to life in prison.

Marilyn Stowe instructed a pathologist to review the medical notes of both infants. The pathologist discovered that one of the babies had in fact died from a viral infection, not cot death. This evidence was not presented in the initial trial. The appeal was successful and the conviction was quashed. This case raised important questions about the reliability of expert evidence.

Ernest Saunders: freed after a dementia diagnosis

Ernest Saunders, along with three other men, were part of the “Guinness Four” who were accused of being involved in a scheme to fraudulently increase the price of Guinness shares. Following a protracted trial, Saunders was found guilty of conspiracy, theft, and false accounting. He was sentenced to 30 months in prison.

Ernest Saunders only served 10 months of his sentence before being released. His doctors maintained that he was suffering from pre-senile dementia, and he “couldn’t remember three numbers backwards or the name of the US president.” A neurologist also claimed that Saunders’ brain was small for a man his age and showed evidence of shrinking.

Questions were raised about the outcome after Ernest Saunders made a “recovery” following his release. His subsequent return to business raised further questions about the evidence that led to his early release. Some professionals have questioned whether this case has led to heightened caution when considering capacity and fitness in cases where dementia and cognitive impairment are diagnosed.

When should I hire an expert witness?

Examples of when an expert witness may be needed include:

  • Fitness to stand trial
  • Diminished responsibility
  • Causation in personal injury or medical negligence
  • Assessments of sexual offending, violent behaviour offending, arson, and stalking
  • Cognitive and psychological assessments
  • Advice on appeals

Talk to our experts

To hire an expert witness, you may make contact with us via our simple online contact form, call us on 01865 587 865 or by requesting a call back from our team via the link below.