Anwan Glover -- who starred in the "The Wire" and "12 Years a Slave" -- has been sitting in a jail cell for over a week now after getting busted on firearm charges.

The veteran TV and movie actor was arrested in Washington D.C. on June 26 and booked for unlawful possession of a firearm -- a misdemeanor -- after cops say they searched his car during a traffic stop and discovered an unregistered handgun in Glover's Jeep.

According to docs, obtained by TMZ, police were notified to be on the lookout for a white Jeep with a driver who was allegedly brandishing a gun out the window. Cops say they pulled over Glover because his ride matched the description and was making multiple lane changes without signaling.

Officers say they asked Glover if he had any weapons, and he said no. He also said no when they asked if they could search the vehicle but cops did it anyway, claiming probable cause.

The officers say they found a loaded Smith & Wesson MP Shield 9mm tucked between the Jeep's roll bar and roof cover, and then immediately placed Anwan under arrest.

His lawyers filed a motion to have him released on bail ASAP so he could continue working and supporting his family. They say he denied any knowledge of the gun in the vehicle, and also argued cops had no business targeting him in the first place.

While cops say Glover's Jeep matched the description they were given, his attorneys say that's BS, and his Jeep is totally different.