The attorney general will try to persuade the court of appeal today that expert witnesses who give flawed evidence in court cases - such as the paediatrician Sir Roy Meadow - should not be immune from disciplinary action by their regulatory bodies.

Lord Goldsmith is intervening in an appeal by the General Medical Council against a ground-breaking high court ruling last February that experts should not face disciplinary action over their courtroom evidence unless a judge reports them to their regulatory body.

Mr Justice Collins made the ruling when he quashed GMC findings that Professor Meadow, who gave misleading statistical evidence at the murder trial of Sally Clark, was guilty of serious professional misconduct and should be struck off the medical register.

The judge not only cleared Prof Meadow, who was reported to the GMC by Mrs Clark's father; he ruled that expert witnesses should not be subjected to disciplinary proceedings at all if disgruntled parties in court cases complain, but only if a judge refers the case to the regulator.

Mr Justice Collins made new law in holding that a longstanding rule which protects witnesses from being sued for negligence or defamation over evidence they gave in court also bars disciplinary proceedings against them, except for the rare case where a judge reports them.

Without such a rule, he said, the administration of justice would be harmed because of the risk that professionals either would not give their evidence freely or would refuse to be involved in court cases altogether.

The far-reaching ruling applies not only to doctors but to the whole range of professionals who give expert opinions in court, including surveyors, accountants and actuaries.

Several government departments are backing the attorney general in intervening in the case.

Lord Goldsmith, who sees the issue as so important that he will argue the case personally in court, insists that the public needs protection from experts who go beyond their expertise or express views unsupported by the evidence.

He will tell the master of the rolls, Sir Anthony Clarke, Lord Justice Auld and Lord Justice Thorpe that Mr Justice Collins should have confined his judgment to the Meadow case and should not have established a near-immunity which was never argued for by any party in the case.

The attorney contends that allowing the judgment to stand would cut across the rules governing a large number of regulatory bodies, some of which are under an obligation to investigate all complaints.

Prof Meadow will remain on the medical register even if the GMC succeeds in its appeal. The doctors' regulatory body is not arguing that the order to strike him off should be reinstated.

Lord Goldsmith will make no submissions about Prof Meadow, but will concentrate his arguments on the immunity issue.

Sir Roy told the jury at Mrs Clark's 1999 trial for the murders of her two baby sons that the odds against two natural baby deaths in a family such as hers were 73 million to one. His evidence was seriously misleading because it took no account of common environmental and genetic factors.

She was convicted and served nearly four years in prison before her convictions were overturned on a second appeal in 2003.

The convictions were quashed largely because Alan Williams, the pathologist who carried out postmortems on the two babies, had failed to disclose crucial medical evidence to the defence. Prof Meadow's evidence was a secondary reason for allowing the appeal.

The GMC accepted that he had given his evidence in good faith but told him he should not have strayed into areas outside his expertise.