A team run's student body left. B3 leaves the field of play to avoid A team blockers. B3 chases the play in team A team area for 15 yards or more then returns in bounds and makes the tackle. NCAA rules.

No foul for Team B leaving field and coming back in.

Legal under NF rules.
 

Before a change of team possession B or R can accidentally go out of bounds and reenter without penalty.

If they go out of bounds intentionally its a penalty for illegal participation.

Bottom line is that this is a judgement call in the eyes of the covering official.

NCAA? I'm not sure.

Re: Legal under NF rules.
 

Seeing as TXMike is from Texas, where they use NCAA rules, there is your answer.

So this means by NCAA rules a defender can leave the field of play and return when it is to his benifit????????

Team B can do so. Team B is normally the "defender" but if there is a change of team possession they become offense (but remain as team B.

9-6-1 states that "if a player is blocked out of bounds and returns during the down, he shall return at the first opportunity."

9-6-2 states that "during the down, no player shall intentionally go out of bounds and return."

I think under 9-6-2 you have a foul on B. He intentionally went OOB to avoid the block and stayed there during the play. Illegal Participation.

You must be quoting Fed rules. This situation was posted as a NCAA question and under NCAA rules, there was no foul.