The 24-year-old Nigerian is accused of trying to blow up a Northwest Airlines flight from Amsterdam to the /*United States*/ by detonating explosives in his underwear on Christmas Day last year.
A judge entered a not guilty plea on his behalf. Abdulmutallab is acting as his own lawyer, but he's being advised by lawyer Anthony Chambers.
Chambers suggested on Thursday that he will challenge the government's case against the defendant.
The Associated Press contributed to this report.