Anyone who has a favorite NFL team or plays fantasy football has experienced it. Your favorite team or one of your fantasy studs rips off a highlight-caliber play for a big gain only to see an illegal motion penalty negate the positivity.
What is an illegal motion, and how do the NFL’s officials enforce it?
Here’s a dive into the details.
The NFL’s Illegal Motion Penalty, Explained
Several rules are put in place and strictly enforced by NFL officials to govern offensive alignment and movement before the snap. The intent is to govern the offense’s ability to compel the defense into committing an infraction.
The three most common categories of pre-snap, motion-related infractions called against the offense are the False Start, Illegal Shift, and Illegal Motion penalties. As for the latter, the definition is located in Rule 7, Section 4, Article 2, Item 2 (Eligible Receiver) of the NFL’s 2024 Rule Book. It states the following:
- Any eligible backfield player who changes his stance does not have to come to a complete stop prior to the snap, as long as his actions are not abrupt (false start) or forward (illegal motion).
Additional categories of illegal motion penalties are defined in Section 4, Article 8, where the following is stated:
- When the ball is snapped, one player who is lined up in the backfield may be in motion, provided that he is moving parallel to or away from the line of scrimmage. No player is permitted to be moving toward the line of scrimmage when the ball is snapped. All other players must be stationary in their positions.
- If an eligible receiver who is on the line moves to another position on the line (not forward), he must come to a complete stop prior to the snap. If he does not come to a complete stop, it is Illegal Motion.
- It is also illegal motion if a T-Formation Quarterback goes in motion and fails to come to a complete stop for at least one full second prior to the snap.
The penalty for this infraction is a loss of five yards from the original line of scrimmage and a replay of the down.
The difference between illegal motion and illegal shift infractions is minor but clearly defined in Rule 7, Section 4, Article 7.
The Difference Between a False Start and an Illegal Motion
A more common occurrence, but categorized similarly to illegal motion, is the penalty for a false start. The definition for this penalty can be found in Section 4, Article 2 and states the following:
- It is a false start if the ball has been placed ready for play, and, prior to the snap, an offensive player who has assumed a set position moves in such a way as to simulate the start of a play, or if an offensive player who is in motion makes a sudden movement toward the line of scrimmage. Any quick abrupt movement by a single offensive player, or by several offensive players in unison, which simulates the start of the snap, is a false start, and the official shall blow the whistle immediately, whether the snap is made or there is a reaction by the defense.
The penalty for this infraction is a loss of five yards from the line of scrimmage.
A key distinction between this infraction and the illegal motion infraction is in the enforcement. While the penalty for illegal motion results in a five-yard loss and a replay of the down just as it does for a false start, the officials will whistle the play dead in the case of a false start; in the case of illegal motion, the officials will allow the play to proceed and then apply the penalty afterward.