Kevin Barron MP (Labour, Rother Valley) told a four-hour debate on the Health and Social Care Bill last week that the GMC was already set on the change to the lesser standard.
The GMC member told the House of Commons: 'The civil standard of proof will apply in any case without the Bill.
'The GMC decided that quite a long time ago, upsetting the profession well before ministers did so by publishing the Bill.'
However, Mr Barron said that a more rigorous proof standard would be required on a sliding scale, depending upon the seriousness of the allegation that is made against the doctor.
'The GMC's legal advice makes it clear that the civil standard of proof is not a rigid criterion by which facts are to be judged, but is to be tailored to the facts of any given case,' he added. 'It is often said that the more serious the facts alleged, the more cogent and compelling will be the evidence required.'
Mr Barron, who also sits on GMC fitness-to-practise panels, added that: 'It is questionable whether it is appropriate to retain the criminal standard of proof in a protective rather than a criminal jurisdiction, especially when the concerns relate to a doctor's health or performance.'
Andrew Lansley, Conservative party shadow health secretary, questioned whether medical directors of PCTs should be responsible officers to monitor conduct because of a 'conflict of interest' and asked whether they would be in place by April 2009.
Health minister Ben Bradshaw said: 'Having responsible officers should mean that we can avoid a situation where many cases that could be managed and resolved locally have to go to the top.'