According to the pilot, he landed the airplane on the centerline of the runway and the airplane began to veer to the left. He applied right rudder pressure; however, the airplane continued to the left. It traveled off the left side of the runway and came to rest inverted in a ditch, which resulted in substantial damage to the fuselage and right wing. The pilot indicated that the left brake "locked up" during the accident sequence. A postaccident examination of the airplane revealed that there were no malfunctions or anomalies with the brake system that would have precluded normal operation prior to the accident.