The trial of five alleged 9/11 co-conspirators resumed Tuesday in Guantanamo.
The defendants include Khalid Sheikh Mohammed, the self-professed mastermind behind the attacks.
He and the others face 2,976 counts of murder.
The trial is taking the form of a 'special tribunal for wartime offenses,' a unique blend of civilian trial and military court martial.
The proceedings have been dogged with problems, though.
Proceedings ground to a halt on Monday as defense attorneys challenged the recording systems in the court-room, amid concerns that mics could pick up confidential conversations between attorneys and their clients.