On September 3, 2008, Arthur and fellow former Kansas Jayhawks teammate Mario Chalmers were excused from NBA's Rookie Training Camp following a marijuana-related incident. Police responding to their hotel room following a fire alarm at 2:00 a.m. claimed that the room smelled strongly of marijuana but none was found and no charges were filed. Fellow NBA rookie Michael Beasley was also reported to have been in the room at the time, but was not asked to leave camp. Beasley was later fined $50,000 for his involvement in the incident