Do you flag this for illegal motion?
 

(Any of the major USAn codes.) Team A is a bit confused and taking extra time breaking the huddle. A1, thinking he's a 12th player, runs off as the huddle breaks. Team A snaps the ball just before A1 gets over the sideline. Do you flag the illegal motion, or do you think that would be against the spirit of the shift rule?

What if A1 gets out of bounds before the snap? Did his participation in a shift get erased when he became a non-player? Or does he remain a player because he wasn't substituted for?

FED: illegal motion.
NCAA: False start, kill it as the play starts.
NFL: not sure, but it's probably one or the other.

If he ends up OOB before the snap, play on (assuming all other positioning/numbering requirements are met at the snap). It's not against the rules to play with 10 players.

NF:

It can't be illegal motion if he isn't moving forward at the snap.

If he's going off the field and gets behind the wing, who in this day and age, should be on or close to the sideline, it's more likely than not to be nothing. Unless it creates a six man line for A, then you would have illegal formation.
A gains no advantage by playing with 10 players. It would be real difficult or picky to get an illegal shift out of this scenario.

Not sure how you would get false start under NCAA code?

If the player doesn't pause for a second before sprinting to the sideline, it's illegal motion.
If he's running toward the LOS to get OOB, illegal motion.
If another player is in motion, it's illegal shift.
If he's supposed to be the 7th on LOS, illegal formation.
<Live ball fouls!>

If he gets OOB and there's still 7 on the line, nothing.

Because he ran off as the huddle broke and the players weren't ever set. By rule, this is a false start.

Breaking the huddle would be a shift.

7-2-6: After a huddle or shift all 11 players of A shall come to an absolute stop and shall remain stationary simultaneously without movement of hands, feet, head or body for at least one second before the snap.

PENALTY:illegal shift (Art. 6) – (S20);

ART. 7 . . . Only one A player may be in motion at the snap and then only if such motion is not toward his opponent's goal line. Except for the player "under the snapper," as outlined in Article 3, the player in motion shall be at least 5 yards behind his line of scrimmage at the snap if he started from any position not clearly behind the line and did not establish himself as a back by stopping for at least one full second while no part of his body is breaking the vertical plane through the waistline of his nearest teammate who is on the line of scrimmage.

PENALTY: illegal motion (Art. 7) – (S20);

Assuming the huddle was more than 5 yards from the LOS, as most are, he is already established as a back and he doesn't turn towards his opponent's goal line so it is not illegal motion.

At best its illegal shift, it sure isn't a false start.

Rule: 7-1-7

ART. 7 . . . After the ball is marked ready for play and before the snap begins, no false start shall be made by any A player. It is a false start if:

a. A shift or feigned charge simulates action at the snap.

b. Any act is clearly intended to cause B to encroach.

c. Any A player on his line between the snapper and the player on the end of his line, after having placed a hand(s) on or near the ground, moves his hand(s) or makes any quick movement.

As a wing, if he's behind me, he's off the field.

NCAA rules, it's 7-2-b-5. Clearly a false start, by rule.

And of course if he's behind you he's off the field. You're on the white, so naturally he's off the field. I wouldn't step forward to put him behind me, though.

Sorry, we were comparing apples and tomatoes.;)