A judge said "no" Wednesday to the argument by the platinum-selling artist's that the gun was found during an unjustified police stop of his Maybach sports car after a July 2007 concert.
Prosecutors say the stop was warranted because the car had no insurance and a suspended registration.
The judge did throw out another piece of evidence: the rapper's statement to police that he had a bit of marijuana in his pocket. He isn't charged with drug possession.
Ja Rule, whose real name is Jeffrey Atkins, has pleaded not guilty. The 33-year-old faces up to four years in prison if convicted.
