What kind of foul?
 

During a scrimage play, A12, while he is about to be sacked, throws the ball toward A77. a: The ball hits A77 in the back and falls to the ground. b: A77 catches the ball.

In either case, is it intentional grounding, or is it illegal touching?

Sounds like intentional grounding in both cases. It can't be illegal touching because illegal touching only applies to legal forward passes and intentional grounding is an illegal forward pass.

If you did not rule IG, then you'd have illegal touching in (b) but not (a). 7.5.13 Situation A

IMHO, it would be hard to argue against IT in (b).

If A12 legally threw a pass and it hit A77 in the back, is that legal?

Which level rule book is that quote from?

There is no foul for a legal pass that simply strikes an ineligible player. NFHS rule 7-5-13 states that that illegal touching applies to an ineligible A player that "bats, muffs, or catches" a legal forward pass. The action described above does not meet the definition of a bat, muff, or catch. There has to be an intent to touch the ball for it to be illegal touching.

There is no foul for a legal pass that simply strikes an ineligible player. NFHS rule 7-5-13 states that that illegal touching applies to an ineligible A player that "bats, muffs, or catches" a legal forward pass. The action described above does not meet the definition of a bat, muff, or catch. All three actions require an intent to touch the ball.

It sure does in the second scenerio, but not the first.

NFHS: legal. Illegal touching is intentional, and accidental touching (getting hit in the back) is ignored.

7.5.13 SITUATION A: Ineligible receiver A2 is behind, in or beyond his neutral
zone when a forward pass by A1: (a) accidentally strikes him in the back; or (b)
is muffed by him; or (c) is caught by him. RULING: In (a), there is no infraction,
but in (b) and (c), it is illegal touching. The acts in both (b) and (c) are intentional
and not accidental as in (a). Although ineligible downfield could also be called,
the loss of down provision for illegal touching will see that penalty most often
applied.

What is the rule about accidental touching in NCAA and NFL? I did a quick glance in each of those rules, but it would appear that accidental touching of a pass by an inelligible receiver is illegal in NFL I couldn't find the specific rule in NCAA rules.

IG would be a bigger punishment to A but I suppose it depends if it truly is IG or not.

bsaucer, the illegal touching rule in NCAA is almost identical to the Fed rule.

7-3-11:

Illegal Touching

ARTICLE 11. No originally ineligible player while inbounds shall intentionally
touch a legal forward pass until it has touched an opponent or an official (A.R.
5-2-3-I and A.R. 7-3-11-I-III).

PENALTY—Five yards from the previous spot [S16].

Under the NF code, INTENT is a requirement of both Illegal Touching (as explained above) and both types of an Illegal Pass relevant to this question.

NF: 7-5-2-c, "a pass intentionally thrown into an area not occupied by an eligible offensive receiver."

NF: 7-5-2-d, "A pass intentionally thrown incomplete to save loss of yardage or to conserve time (exception: immediately after receiving a direct hand-to-hand snap).

The question failed to indicate whether, or not, there was an eligible receiver in the vicinity of A77, or whether the pass was intended for A77. Those types of illegal forward passes are judgment calls that MUST include consideration of intent.

Canadian Ruling
 

CANADIAN RULING:

An illegal forward pass and possibly Deliberate Grounding.

If both: B chooses which to apply.

In fact, it's superior, since it explicitly prohibits intentionally touching a forward pass. The NFHS rule mentions "bats, muffs, or catches," which imply intent, but who cares what the ineligible is trying to do? Intentional touching is what we want to prohibit.

True. The most reasonable argument would be that he was trying to throw it to somebody, just the "wrong somebody." Therefore, he wasn't trying to throw it away. Conversely, if he just throws it up and A77 runs under it, just because A77 caught it doesn't negate IG.