Responsibility

[sj]

For the purpose of asking this question in a simple way I’ve written out 8-7-1 as follows:

Responsibility: 8-7-1: The team responsible for the ball being out of bounds behind a goal line or being dead in the possession of a player on, above or behind a goal line is the team whose player:

1) carries the ball on, above or across the goal line
2) or imparts an impetus to it that forces it on, above or across the goal line
3) or is responsible for a loose ball being on, above or behind the goal line.
 
The question is...Is there a play where clause #3 comes into use that isn’t already covered by clauses #1 and #2? The use of the word “or” for the third clause seems to imply that there would be one.

[sj]

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[ElvisLives]

For the purpose of asking this question in a simple way I’ve written out 8-7-1 as follows:

Responsibility: 8-7-1: The team responsible for the ball being out of bounds behind a goal line or being dead in the possession of a player on, above or behind a goal line is the team whose player:

1) carries the ball on, above or across the goal line
2) or imparts an impetus to it that forces it on, above or across the goal line
3) or is responsible for a loose ball being on, above or behind the goal line.
 
The question is...Is there a play where clause #3 comes into use that isn’t already covered by clauses #1 and #2? The use of the word “or” for the third clause seems to imply that there would be one.

Not an English expert, but I did pay attention in my English classes. By what I understand, your confusion regarding 2) and 3) is well founded. They do appear to be redundant, as written. I don't know how a player could impart the impetus on the ball that forces it on, above, or across (behind) the goal line, and then NOT be responsible for the ball - loose or otherwise - being on/above/behind the goal line.
However, if, in 2) you think of the impetus as having been imparted on it in the field of play, and then traveling on/above/across (behind) the goal line, then that would distinguish 2) from 3). 3), then, would be cases in which a player imparted impetus on the ball from the end zone, where it then crossed back into the field of play, and then - with no new impetus - returned on/above/across (behind) the goal line (where it became dead).
That's the best explanation I can offer.

[sj]

...I don't know how a player could impart the impetus on the ball that forces it on, above, or across (behind) the goal line, and then NOT be responsible for the ball - loose or otherwise - being on/above/behind the goal line....

I believe you're correct on this. Maybe it involves two different players. But it's an A-B-A situation and goes in the highly unlikely category.

A 1/10 @ A5. Running back A34 runs to the A7 where he fumbles. B93 picks up the ball and runs, but then fumbles at the A2. The ball rolls into the end zone where QB A12 picks up the ball and runs. A12 is still in the end zone when he fumbles and the ball goes out of bounds over the end line.

So A12 isn't responsible for the ball going across the goal line because B93 was. But after possession was regained he was at fault for the ball being loose behind the goal line. I certainly don't know if this is what is intended or correct but none the less.

[ElvisLives]

I believe you're correct on this. Maybe it involves two different players. But it's an A-B-A situation and goes in the highly unlikely category.

A 1/10 @ A5. Running back A34 runs to the A7 where he fumbles. B93 picks up the ball and runs, but then fumbles at the A2. The ball rolls into the end zone where QB A12 picks up the ball and runs. A12 is still in the end zone when he fumbles and the ball goes out of bounds over the end line.

So A12 isn't responsible for the ball going across the goal line because B93 was. But after possession was regained he was at fault for the ball being loose behind the goal line. I certainly don't know if this is what is intended or correct but none the less.

A12 was NOT responsible for the ball crossing his goal line and then becoming dead behind his goal line. So, even though he was the last player in possession of the ball, and he fumbled the ball, the impetus for the ball having crossed the goal line (where it then became dead behind the goal line) was B93's fumble. The result of that down is a touchback.
The key is that, AFTER the impetus is imparted on the ball, that impetus must cause the ball to be on/above/across (behind) the goal line AFTER being in, or getting into, the field of play, even if that means the ball must leave the end zone, travel into the field of play, then - somehow - travel back on/above/across (behind) the goal line.
A player that gains possession of the ball in his end zone, then fumbles, passes, or kicks the ball and it goes OB from his end zone - without traveling into the field of play - is NOT responsible for the ball being dead in the end zone. In all of these cases, the NATURAL result of the down is a touchback. However, in the cases of a forward pass (illegal) and a kick (illegal), the penalty will result in a safety.

[sj]

Good explanation. Works for me.