McNamee filed a motion with U.S. District Judge Keith Ellison in Houston earlier this month, saying Hardin should no longer be allowed to represent Clemens because he also once represented Andy Pettitte, Clemens' former teammate. Pettitte has testified that Clemens informed him in 1999 that he used human growth hormone.
Hardin, in a motion filed Monday, said he only represented Pettitte for four days and said Pettitte never signed a contract or paid legal fees.
Hardin said another "unconflicted" lawyer would question Pettitte if he's ever called as a witness in Clemens' defamation suit against McNamee. Hardin also said McNamee had no constitutional right to call for Hardin's disqualification on Pettitte's behalf.
Hardin also said he and his firm, RH&A, have invested too much time -- and Clemens has invested too much money -- in the case to end their relationship now.
"During the course of their legal work, Hardin and RH&A have acquired significant knowledge of and insight into matters directly related to this lawsuit," the filing said. "The loss of that knowledge and insight due to disqualification would severely prejudice the prosecution of Clemens' defamation claims and adversely affect Clemens financially because he would have to hire new counsel and compensate them for their time in getting up to speed on the case."
McNamee's claims against Clemens first surfaced in the Mitchell Report on drug use in baseball.
McNamee also asked Ellison to dismiss the defamation lawsuit on grounds that his statements to baseball investigator George Mitchell were protected by "absolute immunity" through a deal he struck with federal prosecutors.
Hardin did not respond to that request in Monday's filing. An initial conference is scheduled for April 9.