On October 26, about 1245 eastern daylight time, and Mooney, M-20J, N201SE, registered to a private individual, and operated by Embry-Riddle Aeronautical University, as a Title 14 CFR part 91 instructional flight, collided with a runway sign during the landing rollout at Deland, Florida. Visual meteorological conditions prevailed, and no flight plan was filed. The aircraft incurred substantial damage. The commercial-rated flight instructor, and dual student were not injured. The flight originated from Deland, Florida, the same day, about 1200. The flight instructor stated that he was providing instruction to a private-rated pilot seeking a commercial certificate. The instructor further stated that the student had just made an excellent landing, but during the landing rollout he applied violent pressure to the right brake, which moved the nose about 70 degrees to the right, in a skid toward the right side of the runway. The instructor said that he immediately took control of the airplane from the student, but the student maintained his feet on the brakes, and the airplane collided with a runway sign, incurring substantial damage. The student stated that the touchdown was smooth, and the rollout was on the centerline of the runway. The student further stated that he applied the brakes, and it looked to him as if the left brake didn't seem to take effect. The student stated that it is possible that he could have been just using the right brake to stop the aircraft, and upon application of the brakes the aircraft started skidding. The student said he then transferred controls to the instructor, but the airplane was traveling too fast, and it went into the grass, and one wing collided with a runway sign. Under the supervision of an FAA inspector, the operator conducted a postaccident examination of the aircraft, and a functional check of the brakes on both the left and right pilot positions, as well as removed and checked both the left and right main landing gear brake pads. The examination did not reveal any preexisting malfunctions to the aircraft, or its systems. In addition, a ferry permit was obtained, and the aircraft was ferried to an independent authorized Mooney service center, where an evaluation was conducted on the steering and brake systems, and no abnormalities were observed.