A doctor who gave evidence in the case of Sally Clark, wrongfully convicted of murdering her two baby sons, has appeared before the GMC.
Sally Clark was freed in January 2003
Dr Alan Roy Williams, based in Macclesfield, Cheshire, is charged with serious professional misconduct.
The General Medical Council has heard allegations he did not disclose evidence Mrs Clark's second baby Harry had a severe bacterial infection.
His counsel said Dr Williams does not admit any wrongdoing.
Mrs Clark spent more than three years in prison.
She had always denied smothering her first son, Christopher, when he was 11 weeks in December 1996 and shaking her second baby Harry to death in January 1998 when he was eight weeks old.
Dr Williams carried out post-mortem examinations on both children.
It is alleged that in his report, written statement and oral evidence relating to Christopher, he was incompetently self-contradictory, and failed to "use his best endeavours" to express fair, accurate and objective expert opinions.
The appeal that cleared Mrs Clark was told by prosecutors that Dr Williams was aware of microbiological tests which had shown that Harry had the bacteria staphylococcus aureus in his body, which was the most likely cause of death - but did not reveal this at the November 1999 trial.
Dr Williams sat quietly before the GMC hearing as the list of charges against him were read out. They took 28 minutes to read. The hearing is expected to last for four weeks.
Dr Williams faces charges that, while acting as an expert witness at the crown court, he contradicted his opinion of a post-mortem examination, failed to give an adequate cause of death and failed to discharge the duties of a competent pathologist.
On a second post-mortem examination it is alleged that Dr Williams carried out examinations he was not competent to perform and he failed to provide comprehensive expert evidence in advance for a trial.
It is also alleged that the consideration and treatment shown by Dr Williams in both post mortem examinations was such that it impaired the reliable evaluation of the evidence of cause of death.
He will also face charges that he failed in his duty as an expert witness.
Roger Henderson QC, for the GMC's professional conduct committee, told the central London hearing: "This case is not going to permit anybody, neither the committee or the public, to be able to decide why Christopher Clark or Harry Clark died.
Dr Alan Williams denies professional misconduct
"The evidence is going to focus on the work, conduct, acts and omissions of Dr Williams and therefore it will be a necessarily incomplete presentation of the evidence of what occurred relating to the deaths of these two boys."
The GMC investigation was triggered by a formal complaint from Martin Bell, who was Mrs Clark's MP at the time of her conviction.
But James Turner QC, for Dr Williams. called for the case to be thrown out or adjourned, arguing there had been a "scandalous delay" in bringing it.
The death of Mrs Clark's son Christopher in December 1996 was initially thought to have been due to a breathing problem.
But that was reassessed following Harry's death in January 1998.
Sally Clark was convicted of killing both boys in November 1999.
However, she was freed after her second appeal in January 2003.
The case continues.