FYI
Directly from the rulebook:
Roughing the Passer
(Rule 12, Section 2, Article 8)
"(a) Roughing will be called if, in the Referee's judgement, a pass rusher clearly should have known that the ball had already left the passer's hand before contact was made...once a pass has been released by a passer, a rushing defender may make direct contact with the passer only up through the rusher's first step after such release (prior to second step hitting the ground)..."
"(e) A rushing defender is prohibited from forcibly hitting in the knee area or below a passer who has one or both feet on the ground... Note 2: It is not a foul if the defender swipes, wraps, or grabs a passer in the knee area or below in an attempt to tackle him."
"(g) When the passer goes outside the pocket area and either continues moving with the ball (without attempting to advance the ball as a runner) or throws while on the run, he loses the protection of the one-step rule provided for in (a) above, and the protection against a low hit provided for in (e) above, but he remains covered by all the other special protections afforded a passer... as well as the regular unnecessary roughness rules applicable to all player positions..."
Now you know.
