IG or Not

[fudilligas]

Team B is leading 21-14 with less than 2 minutes remaining in the game with the ball on the B-25....The QB for Team A is being chased and just before he is tackled he throws a backward pass which goes OB at the B-35....Is this IG even though the ball was thrown backwards and there was a loss of yardage....or  is it IG because he threw the backward pass OB to conserve time

[GA Umpire]

Team B is leading 21-14 with less than 2 minutes remaining in the game with the ball on the B-25....The QB for Team A is being chased and just before he is tackled he throws a backward pass which goes OB at the B-35....Is this IG even though the ball was thrown backwards and there was a loss of yardage....or  is it IG because he threw the backward pass OB to conserve time

A backward pass cannot be illegal by definition.  7-4-1. 7-5-2.
If the QB tosses the ball backward and oob to conserve time, it is totally legal.  Redding's, P. 43.

[NVFOA_Ump]

Agreed, IG only applies to forward passes.  Backward passes are always legal regardless of how “bad” they look.

[AlUpstateNY]

Agreed, IG only applies to forward passes.  Backward passes are always legal regardless of how “bad” they look.

Not only "legal", but backward passes remain LIVE after being grounded.

[HLinNC]

It isn't IG at all.  It's the next down at the B35.

[AlUpstateNY]

It isn't IG at all.  It's the next down at the B35.

You are correct in suggesting "Intentional Grounding" applies ONLY to "Forward Passes". NFHS:7-4 covers "Fumble & BACKWARD pass, 7-4-2 advises, "If a fumble or BACKWARD PASS is caught or RECOVERED by any player, he may ADVANCE. " NEVER blow a backward pass dead simply because it might be incomplete (Behind, at or Beyond the NZ).

NFHS 2-31-6 confirms that, stating, "A backwards pass ends when it is caught, RECOVERED or is Out of bounds."

[Ia-Ref]

Any player at any time can throw the ball backward.  If it goes oob, the clock stops.
The next down will start where the ball went oob.