The Ohio State football program had to play in at least two games in which Michigan was engaged in illegal advanced scouting operations. Connor Stalions was the ringleader of those operations, and Michigan has tried to claim that he was a rogue agent.
Jim Harbaugh claimed he had no knowledge of the scheme. The NCAA didn't buy that, and essentially made it impossible for him to ever coach college football again. Sherrone Moore also tried to claim innocence from the scheme, but the NCAA didn't buy it either.
Both the university and Moore had appealed the ruling from the NCAA in protest of their innocence.