An illegal shift is a penalty in Football that is called on the offense when a player shifts illegally or performs an illegal motion before or simultaneously as the ball is snapped. This is similar to the illegal motion and illegal formation penalties. There are three main rules that define an illegal shift: a player must not be in motion and be set at the time of the snap, all eleven players must be set at the time of the snap, and only one player can be in motion at a time. If any or all of these rules are broken, an illegal shift can be called. An illegal shift penalty results in a 5 yard loss for the offense.
Most often, an illegal shift occurs when a team is in a hurry, usually at the end of close games, and a player does not completely set before the snap. The defense, luckily, does not have to worry about illegal shifts being called on them.