Tim Montgomery has asked the Court of Arbitration for Sport (CAS) to annul his two-year doping ban because of an alleged conflict of interest.
The former 100m world record holder was suspended in December for taking banned substances from US laboratory Balco.
But Montgomery's lawyers said the head of the CAS arbitration panel had not revealed that his firm also represented the World Anti-Doping Agency (Wada).
"This clear conflict of interest is egregious," stated their letter to CAS.
"It significantly undermines the integrity of the entire CAS process.
"It is demanded that CAS immediately vacate the arbitration award...and dismiss the doping charges brought against Mr Montgomery."
In the letter, lawyers Robert W McFarland and Amy Morrissey Turk said barrister Yves Fortier had not advised Montgomery that his law firm Ogilvy Renault represented Wada.
But CAS secretary-general Matthieu Reeb, to whom the letter was addressed, said that the appeal was wrongly directed.
"Any request for annulment of a CAS award can be brought before the Swiss Federal Tribunal only," he said.
Montgomery announced his retirement from athletics after being handed the suspension on 13 December.