Major Michael Mori, the defence lawyer for terror suspect David Hicks, could be removed from the case after threats from the chief US prosecutor to charge him under the Uniform Code of Military Justice.
The intervention may derail Hicks' trial and possibly prompt his return to Australia.
It would take months for a new lawyer to get to grips with the case and the new military commission process.
Prime Minister John Howard has told Washington that any action leading to further delays would be unacceptable and would prompt him to demand the return of Hicks, 31, after being held for five years at the US base at Guantanamo Bay.
