The General Medical Council decision to strike Professor Sir Roy Meadow off the medical register was "excessive and wrong", a court has heard.
Sir Roy denied serious professional misconduct
The GMC found the paediatrician guilty of serious professional misconduct over evidence given in the trial of Sally Clark, accused of murdering her sons.
But Sir Roy has taken the case to the High Court to appeal against the verdict reached last July.
His legal team also said he should not have been found guilty.
Mrs Clark's 1999 conviction for murdering her two sons was quashed in 2003.
Sally Clark: Served three years after being wrongly convicted of killing her two sons
Angela Cannings: Served 18 months after being wrongly convicted of killing her two sons
Donna Anthony: Served six years after being wrongly convicted of killing her son and daughter
Trupti Patel: Cleared of killing three of her children
The GMC later said evidence given by Sir Roy had been misleading, although Mrs Clark was actually freed after it became apparent that another witness at her trial, pathologist Alan Williams, had failed to disclose key medical evidence.
Sir Roy also gave evidence as an expert witness in the trials of two other women, Angela Cannings and Donna Anthony, who were both freed on appeal after being convicted of murdering their children.
At Sir Roy's original hearing, the GMC panel said it was vital the public had confidence in experts brought before court and that was why the 72-year-old had to be struck off, rather than be given a lesser penalty.
During Mrs Clark's trial, Sir Roy said the probability of two natural unexplained cot deaths in the family was 73 million to one.
The figure was later disputed by the Royal Statistical Society and other experts said that once genetic and environmental factors were taken into consideration, the odds of a second cot death in the same family were closer to 200 to one.
But Nicola Davies QC, representing Sir Roy, told Mr Justice Collins that Sir Roy had at all times acted in good faith and had no intention to mislead.
She said that although his evidence may have been mistaken, at the time he genuinely believed his testimony was accurate and there was no "wilful or calculated failure" on his part.
Sir Roy had retired from clinical practise in 1998 and, by the time of the GMC hearing, was no longer engaged in any medico-legal work, so Miss Davies told the court issues of patient protection simply did not arise.
"The sanction of erasure was punitive, disproportionate and was required neither to protect patients, nor for the public interest."
However, Mr Roger Henderson QC, for the GMC, said Sir Roy had strayed outside his area of expertise when giving "erroneous, incompetent and unfair" statistical evidence during Sally Clark's trial.
Although he accepted the professor had no intention to mislead, the QC said he had testified that it was "very, very, very unlikely" that Mrs Clark had not killed her sons.
Sir Roy's forensic errors were "compounded by repetition", and Mr Henderson told the court there could be "no valid argument" that he was not guilty of serious professional misconduct.
He added the evidence he gave, albeit unintentionally, was "unfair and misleading".
The case has been adjourned until Tuesday.