B11 mistakingly believes he is his team's 12th player and leaves the field on the opponent's sideline before the snap. Is this a foul?

Nope, no foul. You never said he came back on the field. If he did, during the down, we would have another story altogether.

But leaving the field on the wrong side and leaving his team with 10 players, no foul, just stupid.



Dr.Moore

Agreed, playing with 10 players is legal, just make sure if its the offense with 10 players that they have the right amount of people on/off the line

For those working NCAA and NF rules, this is a dead ball substitution foul under NCAA and as pointed out, no foul under NF rules.
Hate thess little differences like this!!!

I don't work NCAA but what exactly is the foul for? Leaving on the wrong side of the field?

For NF it's still a foul to leave on the wrong side of the field for substitutes and replaced players, but not players.

Dr. Moore: We did have some interesting discussion involving a player who left the field and re-entered during the down a while ago. If you split hairs one may argue there is no foul for a player to re-enter during a down so long as he didn't violate shift or enforcement restrictions. But, I think we all agreed that would be wrong. In that thread I believe Bob M had a pretty logical case of what you should call (Illegal Sub). It had to do with a player filling his own vacancy.

http://www.officialforum.com/showthr...3&pagenumber=1

### NCAA rules call this illegal substitution and it's a dead ball foul (only a 5 yarder). Yes, it is for leaving the field on the other teams sideline OR over the endline.
NCAA applies this foul to players as well as to replaced players.