Doctors and other expert witnesses who give their evidence honestly and in good faith are immune from disciplinary proceedings over anything they say in court, a senior judge at the High Court in London ruled in a ground breaking judgment last week.

Mr Justice Collins held that Roy Meadow, the retired paediatrician who was found guilty of serious professional misconduct and was ordered to be struck off the medical register last year for his role in the Sally Clark murder trial, should never even have been brought before the General Medical Council (BMJ 2005;331: 177

The ruling makes new law by extending to action by regulators the longstanding immunity from civil actions over their evidence that witnesses in court cases enjoy.

The judge said that regulators such as the GMC could take action only if a complaint about an expert witness was referred by a judge to such bodies. That would bar complainants such as Frank Lockyer, Mrs Clark's father, who initiated the GMC case by complaining about misleading statistical evidence on the risk of two …