The Manhattan district attorney's office has said Ferhani wanted to attack a synagogue.
Prosecutors say he bought three guns and a grenade to do so. The buy was a sting.
His lawyers previously said Ferhani was mentally unstable. They have said the prosecution was based on insufficient evidence and dubious tactics.
Ferhani and a co-defendant were arrested last year.
A grand jury declined to indict the men on a top-level terror
conspiracy charge.