The General Medical Council admitted last week a range of past failings but insisted that improvements to its procedures, along with revalidation and local clinical governance, should help ensure that unfit doctors are detected in future.
The GMC's counsel, Roger Henderson, told the inquiry of the circumstances in which the GP Harold Shipman managed to murder dozens of patients undetected: "As a registered medical practitioner, Shipman betrayed his patients and his profession in a way that was not reasonably foreseeable.
"Until he was found to have perpetrated his murders, systems were not designed to take the possibility of such extreme wickedness into account. We were part of the systems which failed to protect Dr Shipman's patients."
Mr Henderson made his speech as the inquiry moved into the final part of its last stage, examining disciplinary systems and the regulatory mechanisms of the GMC.
As the BMJ went to press, a GMC council meeting was expected to approve a paper proposing new procedures for passing on information about complaints to doctors' employers.
Shipman, Britain's most prolific serial killer, is serving a life sentence after being convicted at Preston Crown Court in January 2000 of killing 15 patients. The inquiry, chaired by the appeal court judge Dame Janet Smith, has found that he killed at least 215 patients, mainly elderly women, with lethal doses of diamorphine.
West Pennine Health Authority, which covers Hyde, Greater Manchester, where Shipman practised, was unaware that he had been addicted to pethidine and had a 1976 conviction for forging prescriptions for the drug. He appeared before the GMC but was allowed to rehabilitate himself and return to practice as a GP after working in community health.
After his conviction, the GMC said it had received no information to suggest any misuse of drugs between 1976 and his arrest in 1998. There were complaints about three separate incidents, but none suggested a fundamental problem in the GP's practice.
Mr Henderson said: "The new systems must be based on the generality of doctors but must, where practicable and trying to avoid unwanted consequences, minimise the risk of another Shipman and improve the prospect of catching and preventing criminal activities which could endanger patients as early as possible."
He added: "The risk is best addressed both locally where concerns are likely to arise and to be reliably investigated and nationally where patterns and registration may be best analysed and controlled."
He admitted that there had been unacceptable delays in the GMC's process and that it had not always followed up cases where local trusts were expected to investigate and report back.
Some cases had been closed which should not have been. There had been a lack of consistency in approach between comparable cases, particularly where dishonesty was associated with drug misuse.
Cases were compartmentalised so that once a case was classified as raising issues about the doctor's health it was always treated as a health case.
There had been a failure to follow up undertakings and breaches of conditions, he said, and a failure—before the inquiry into excess child mortality at Bristol Royal Infirmary—to recognise that the GMC was part of a larger regulatory whole.