Expert criticised for changing opinion without justification
This case involved a claim by the Claimant against five potential Defendants, all of whom employed him at some period or periods of his working life. His claim was for pleural thickening with restriction and respiratory disability. It was said that this was caused due to exposure to asbestos whilst at work.
The learned Judge heard from the Claimant and his wife together with three Consultants with expertise in the field of diseases of the chest. There was an expert witness called on behalf of the Claimant and one on behalf of each of the Fourth and Fifth Defendants. Those witnesses had met and discussed the issues. They had prepared a joint report. It was clear that whilst there was some areas of agreement there were also areas of disagreement. The Claimant’s witness had been caused to change his opinion somewhat in cross-examination from that set out in the joint report.
What factors did the Judge consider relevant in deciding weighing up the expert evidence?
Overall, the learned Judge observed that the expert plainly owed a duty to the Court to give his present opinions and not simply to repeat his older views if he no longer held them. However, the learned Judge referred to the fact that the Claimant’s expert seemed to express no new factor in the witness box in moderating his view and it was simply a reevaluation of the evidence. He did not consider that the expert had given a real explanation for resiling from his view set out in the joint statement save that he could not recall the discussions leading up to part of his view. On the other hand the learned Judge did not detect any change of view of either of the Defendants’ experts that were called.
Overall, the learned Judge therefore found that the evidence of the Defendants’ experts was to be preferred.
Further, the Claimant had sought to rely upon the medical records of the Claimant and in particular a record that disclosed a treating Consultant (a Cardiologist and therefore not necessarily within the same field of expertise) had considered the Claimant to have a significant restrictive lung disease. It was said that this supported his case. Overall, the learned Judge considered that his main task was to evaluate the evidence of the medico-legal experts rather than to evaluate the very briefly expressed views of a Consultant.
Whilst it is of course important that an expert gives his or her considered and current view to the Court, whether at the time of writing the report or indeed in the witness box, it is equally important to lend credibility to such a change or shift in view that the expert fully explains why he or she has changed their view. After all, the expert who is forced to change a view because they reconsider some new evidence or can explain the reason for the change, is actually more likely rather than less likely to be accepted at the end of the day. However, an expert that simply changes his or her mind because they have re-evaluated the evidence or perhaps moderated their view for no other reason than they did not think of it early enough is vulnerable to attack on the above grounds.