Dumb question, if there is a face mask on a sack, is it penalized from the previous spot or from the sack? There is a similar play in the case book, but in the book it has the QB fumbling the ball, making it a loose ball play, so it would be from the previous spot. So what if he doesn't fumble? Can I get a reference?

penalized from the spot of the foul/end of the run. Which in your question was a sack, and was the end of the run.
9-4-2-h; 2004.

[Edited by irefky on Nov 8th, 2005 at 09:39 PM]

As far as the rules are concerned, there's no such thing as a sack. It's simply a running play. Penalized from the end of the run.

Ok let me re-word it correctly. A penalty on the defense during a running play where the run ends BEHIND the line of scrimmage is enforced from where?

Unless the run behind the neutral zone is followed by a loose ball, this penalty is enforced from the end of the run.