Explaining False Start vs Offsides vs Illegal Motion

There are so many different penalties in the NFL that it can be confusing and hard to keep up with all of them.  Not only that, there are so many penalties that seem to be the same thing except when they announce the penalty they call it by a different name.  

One perfect example of this is penalties that occur on the line of scrimmage. Some fans will often have a hard time understanding false start vs offsides vs illegal motion. What are false starts, offsides, and illegal motions? 

First let’s understand this:

  • False Start is a penalty on the offense
  • Offsides is a penalty on the defense
  • Illegal motion is a penalty on the offense

A false start is when an offensive player makes a motion that simulates the start of the play after getting set.

Offsides is when a defensive player is in the neutral zone when the ball is snapped.

Illegal motion is when a player is moving towards the line of scrimmage at the snap or when two or more players have motioned before the snap and don’t become set before the play starts. 

These penalties are all 5 yards.

Let’s discuss how the full rules are applied for these penalties and highlight the differences between them.  We will also discuss the reasons for allowing the play to continue on or blowing the play dead.

False Start in Football

A false start in football is a penalty against the offense. Offensive players must remain motionless (with some exceptions) once they become set at the line of scrimmage pre-snap. If an offensive player performs a post-snap motion pre-snap (for example a lineman beginning to block before the snap), a false-start penalty is called. False start is a 5 yard penalty.

So, if you are trying to understand false start vs offsides, just remember that false start is against the offense and offsides is against the defense. If you are trying to understand false start vs illegal motion, remember that false start occurs when a set offensive player jumps pre-snap, but illegal motion occurs when a player or players in motion commit an illegal action while in motion (for example, moving towards the line of scrimmage; more on that later).

The reason false starts exist is:

1. It would be unfair to defenders because the only way they would know the ball is snapped would be to watch the football.  And although defensive lineman are taught to watch the ball, cornerbacks are not. So if wide receivers could move before the snap it would be difficult for defenders to know when the ball was actually snapped and the play began.

2. It would also give the offense an advantage by allowing them to get into post-snap position, which would be a huge advantage for offensive lineman. 

There are, as we noted above, a few exceptions to this rule. Offensive players are allowed to move their shoulders or hands as long as to not make it seem like they are simulating the play starting.

For example, let’s say an offensive lineman goes to the line of scrimmage and gets set. Then the quarterback changes the play at the line of scrimmage due to the alignment of the defense.

The offensive lineman is allowed to twist his shoulders to look back at the quarterback to listen and receive play instructions etc. But once the instructions are received, the lineman must then become set once again before the ball is snapped.

But there are occasions for lineman where no movement is restricted, even for play adjustments. For example, if they get in a three point stance they are not allowed to move or change their stance to a two point stance (because this movement could easily simulate the start of a play and trick defenders). 

The three point stance is where an offensive lineman has two feet on the ground and one hand on the ground, making it a total of three “points” of the body touching the ground.  Two-point stance is where they only have their two feet set, but no hand touching the ground.

As for receivers on the line of scrimmage, once everyone is set they are not allowed to move forward at all, regardless if it is done quickly or slowly.  These eligible receivers are allowed to go from a three point stance to a two point stance if they want (usually only a tight end would do this), but they must come back set for a full second before the snap. 

The players in the backfield or the quarterback under center are allowed to motion and move, but they must not do so quickly or abruptly (as if attempting to trick the defense) or it is considered a false start. 

Also, if these players do go in motion out of the backfield, they are required to come to a stop for a full second or it is also a false start.  When in the shotgun, the quarterback is allowed to move around and call out signals, but they can’t shift their feet real fast or thrust their arms out real fast because if they do it will be called a false start. 

As you can see, the false start penalty has a lot of moving parts. It takes time watching and learning the game of football to understand all the variations of movement and what is not allowed.

Whenever an offense commits a false start penalty, the play will be blown dead and the offense will be assessed a 5 yard penalty. Again, if you are trying to understand false start vs offsides, remember that the offensive player jumping early is a false start, but a defensive player jumping early is offsides.

Illegal Motion in Football

In football, an illegal motion is called when an offensive player performs some type of restricted pre-snap motion. These pre-snap motions are regulated to keep play fair for the defense. Illegal motion is a 5 yard penalty.

The NFL wants to make sure that offensive players aren’t motioning in a way that puts the defense at a disadvantage at the snap.  To do this, they restrict how offensive players can motion and institute rules around what they have to do after motioning. 

There are a couple ways in which an offensive team can commit an illegal motion. 

1. Offensive players can’t be moving forward towards the line of scrimmage at the time of the snap because that would allow them to get a running start at the snap while the defender doesn’t have any realistic chance to do that.

2. If two players get set, and then go in motion at the same time, they have to both get set for a full second before the snap.  If one of the motioning players doesn’t get set before the snap, they will be flagged for illegal motion. 

3. There can be one player in motion at the time of the snap as long as they were never in motion when someone else was in motion (and they must not be moving towards the line of scrimmage).

Some people get hung up on trying to understand illegal motion vs false start. I don’t want to oversimplify it, but the majority of the time it comes down to this: if a set player jumps early, it’s a false start, if a player in motion violates one of the rules listed above, it’s illegal motion. Both are penalties on the offense.

Another difference when comparing false start vs illegal motion is this: false start penalties are blown dead pre-snap, and illegal motion penalties are not. So if you see someone jump and a referee throws a flag and blows the play dead before the snap, it would be a false start penalty.

Offsides in Football

Offsides is when a defensive player is in the neutral zone at the time of the snap.  This usually happens when a player both lines up in the neutral zone and doesn’t realize it or when a quarterback uses a hard count to get them to jump into the neutral zone. 

When offsides is committed, the flag is thrown but the play continues (unless the offsides created a free path to the quarterback, at which time the referees blow the play dead for player protection purposes).

When the defense commits an offsides penalty and the play continues, this creates what is known in football as a “free play”. This means that the offense gets a chance to run a play where no harm can come from it. If the quarterback throws an interception, the interception will be wiped away by the offsides penalty.

So if the offense like the outcome of the free play (let’s say they complete a 15 yards pass for a first down), then they will just decline the penalty and instead accep the outcome of the play.

If they do instead accept the penalty (for example, the outcome of the play was an incomplete pass), 5 yards is assessed from the previous line of scrimmage.  The down is not counted against the offense, so if it was 2nd and 10 before the penalty, it is now 2nd and 5.  If the offense had 5 or less yards to gain on the previous play, they will be rewarded a first down.

Again, when comparing offsides vs false start, remember that offsides applies to the defense and false start applies to the offense.

In summary, false starts and illegal motion penalties are on the offense and offsides is on the defense.  Offsides is when a defender is in the neutral zone at the snap of the ball.  A false start is when an offensive player moves before the snap and illegal motion is when the offense motions before the snap in a way that will give them an unfair advantage over the defense.

Joshua Lloyd

Joshua is lead content creator for basketball and golf at Sports Fan Focus. Golf is a passion of his and he enjoys both playing and watching golf in his spare time. To read more about Joshua, visit the SFF About Us page.

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