An illegal cut is a penalty in Football that is called on a team, usually the offense, when a player performs an illegal cut block. A cut block is a block in which a player blocks an opposing player by diving into their knees from the front. A cut block is normally legal, though considered a dirty play, and most major Football leagues have tried to eliminate the block from the sport. An illegal cut block occurs when a player performs a cut block on a player already engaged in a block with another player. Most of the time, this occurs when an offensive lineman and a defensive lineman are engaged and another offensive lineman performs a cut block on the defender. This penalty results in a 15-yard loss for the offending team.