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Inadequately qualified ‘expert’ witness causes trial to collapse

02 Jul 2019 / COURTS Print

Inadequately qualified ‘expert’ witness causes trial to collapse

The evidence of an inadequately qualified ‘expert’ witness has led to the collapse of a recent trial in Britain involving a multi-million-pound carbon-credit fraud against eight defendants. Problems arose during cross-examination by defence counsel. Over 20 additional fraud trials could now be declared unsafe as a result. 

The individual was engaged by the prosecution to act as an expert witness but, during cross-examination, it quickly became apparent that he lacked the necessary academic qualification, had never read a book on carbon credits, had stored sensitive documents inadequately, and had cut-and-pasted witness statements from previous trials.

The trial judge commented that the person: “… is not an expert of suitable calibre. He had little or no understanding of the duties of an expert. He had received no training and attended no courses. He has no academic qualifications. His work has never been peer-reviewed”. 

Inherent risks

Paul Convery of William Fry says that the case serves as a useful warning about the risks inherent in hiring expert witnesses. The role of the expert witness is to assist the court in making its decision – and not to act as a ‘hired gun’, he says. 

The Supreme Court in Ireland recently addressed the matter in O'Leary v Mercy University Hospital Cork Ltd [2019] IESC 48. Mr Justice MacMenamin referenced expert witnesses' duties, including the duty to address only those areas within the expert's scope of expertise. 

While the expert in those proceedings was judged to have acted appropriately, independently, objectively and in an unbiased fashion, MacMenamin J recommended that the duties of expert witnesses should be outlined in practice directions.  


In 2016, the Law Reform Commission made recommendations about the duties of expert witnesses in its report: Consolidation and Reform of the Law of Evidence. While expert witness immunity still applies in Ireland, the report recommended it should be abolished and replaced with a statutory provision allowing for an expert to be sued if it were established that they had acted with “gross negligence” when giving evidence, or in preparing their expert report. 

Notwithstanding immunity, where an expert witness’s opinions fall short, the judiciary can decide to notify the person’s regulatory body of negative findings against the evidence given. 

Gazette Desk
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