Paul Bergrin's former clients include entertainers Queen Latifah and Lil' Kim.
He was arrested in 2009 and charged with a host of offenses including bribery and prostitution. He's accused of arranging the murder of a government witness in Newark and trying to hire a hit man to murder another witness.
A judge threw out racketeering charges against him last year. But a federal appeals court reinstated the charges in April.
Bergrin is scheduled to go to trial this fall.
On Monday, he will argue pretrial motions in U.S. District Court in Newark.