In vitro fertilisation pioneer Simon Fishel was accused in the High Court this week of "in effect running a private practice" for his own profit while he was a full-time employee of Nottingham University.
The university is suing Dr Fishel for about Pounds 400,000, claiming he indulged in "profit-making activity" without authority.
Tim Dutton QC, for the university, said it may have been Dr Fishel's view of his "own preeminence" that "led him to stray from the proper path". He alleged that while employed full-time by the university, Dr Fishel went on "treatment runs" to foreign clinics, in which up to 20 patients a day were treated, at Pounds 500 a time.
Dr Fishel, Mr Dutton claimed, kept the profits and distributed some of them to other members of the university's embryology staff who went with him. This was without permission and in direct breach of his contract.
Until July 1997, Dr Fishel was a reader in embryology and scientific director of Nottingham University's Research and Treatment Unit in Reproduction (Nurture). The unit was internationally renowned for its pioneering work, "significantly through Dr Fishel".
He was the university's highest-paid employee, earning Pounds 138,000 from Nottingham in 1996.
His complaints that some of the profits made by Nurture were not ploughed back into the unit were "irrelevant to the issues" in the case, said Mr Dutton.
"This is not a case of an academic mistakenly not following the rules. He is in fact abusing the system. This is not mistaken, this is active deception."
Mr Dutton told Mr Justice Elias: "It isn't for us to reason why matters reached such a pass. It may be that Dr Fishel's own view of Nurture's success, and his own pre-eminence, led him to stray from the proper path.
"He was, in effect, running a private practice and not handing over the profits to his employer," he added.
Dr Fishel denied breach of contract and the fiduciary duty he owed the university. He insists that his trips were at all times known about, consented to and encouraged.
The university, he claims, effectively acknowledged that employees might spend up to 20 per cent of their time doing private work.All his work was directed towards advancing knowledge of IVF, Dr Fishel said.
He put his earnings abroad between August 1993 and August 1997 at Pounds 160,000, of which Pounds 50,000 was paid to other Nurture staff.
His lawyers said the university had produced no evidence of a university employee being required to repay money made on outside work.
The hearing continues.