Fumble goes into defensive end-zone out of bounds caused by defense

[Farooq]

Imagine situation. 1st and goal near goal-line of defense.
Offense runs toss play (backward pass). Ball is muffed by halfback.
Defensive player penetrates from the edge and tries to gain possession of loose ball.
While struggling to recover ball defensive player accidently gives impetus to it going into own end-zone and out of bounds.
What is the call?

[ElvisLives]

Imagine situation. 1st and goal near goal-line of defense.
Offense runs toss play (backward pass). Ball is muffed by halfback.
Defensive player penetrates from the edge and tries to gain possession of loose ball.
While struggling to recover ball defensive player accidently gives impetus to it going into own end-zone and out of bounds.
What is the call?

The key here is impetus, and “muffing” the ball, as defined, does not impart impetus, UNLESS the ball had come to complete rest. By your description, it sounds like the ball was still moving, thus, no new impetus. So, the impetus is still from the backward pass. If the ball travels out of bounds behind B’s goal line with no new impetus on it, the result is a touchback, B, 1/10, B-20.

Now, if the ball had, in fact come to complete rest, then is muffed by a Team B player, the muff imparts the impetus on the ball, and, if it travels OB behind B’s goal, the result is a safety, 2-points for Team A, with a free kick by B to follow.

[Farooq]

The key here is impetus, and “muffing” the ball, as defined, does not impart impetus, UNLESS the ball had come to complete rest. By your description, it sounds like the ball was still moving, thus, no new impetus. So, the impetus is still from the backward pass. If the ball travels out of bounds behind B’s goal line with no new impetus on it, the result is a touchback, B, 1/10, B-20.

Now, if the ball had, in fact come to complete rest, then is muffed by a Team B player, the muff imparts the impetus on the ball, and, if it travels OB behind B’s goal, the result is a safety, 2-points for Team A, with a free kick by B to follow.

And if defensive player accidentally kicked or batted moving ball into his end-zone. Does it count for new impetus caused by defense?

[ElvisLives]

Again, let’s be careful about terminology. There is no such thing as “accidentally kicking” the ball. If you judge that the contact with the ball by a player’s foot was unintentional, then that is nothing but the ball being deflected off of that player - i.e., simply ‘touching’ of the ball - and there is no change in the responsibility for the progress of the ball.
By definition, “kicking” the ball is intentionally striking the ball with the foot. So, if it isn’t struck intentionally, then it isn’t kicking.
The same is true for batting. If the ball is not intentionally ‘struck’ with the hand or arm, then it is simply touching of the ball, and that doesn’t impart impetus, unless the ball was at complete rest.

[Farooq]

Thanks for such good explanation, sir. Now I think everything is clear

[ElvisLives]

Thanks for such good explanation, sir. Now I think everything is clear

   You are most welcome!

[dammitbobby]

Again, let’s be careful about terminology. There is no such thing as “accidentally kicking” the ball. If you judge that the contact with the ball by a player’s foot was unintentional, then that is nothing but the ball being deflected off of that player - i.e., simply ‘touching’ of the ball - and there is no change in the responsibility for the progress of the ball.
By definition, “kicking” the ball is intentionally striking the ball with the foot. So, if it isn’t struck intentionally, then it isn’t kicking.
The same is true for batting. If the ball is not intentionally ‘struck’ with the hand or arm, then it is simply touching of the ball, and that doesn’t impart impetus, unless the ball was at complete rest.

To add on to this, the best way I've heard for determining whether or not a loose ball was kicked, was in the heat of the situation, you willfind yourself literally telling yourself, holy crap, he just intentionally KICKED the ball! ...as opposed to it bouncing around and ricocheting off his leg/foot/arm whatever. You're already going to be on high alert anyways because there's a loose ball bouncing around, and believe me if you have eyes on the action you will definitely know when it the ball is intentionally batted or kicked.

[DallasStripes]

To add on to this, the best way I've heard for determining whether or not a loose ball was kicked, was in the heat of the situation, you willfind yourself literally telling yourself, holy crap, he just intentionally KICKED the ball! ...as opposed to it bouncing around and ricocheting off his leg/foot/arm whatever. You're already going to be on high alert anyways because there's a loose ball bouncing around, and believe me if you have eyes on the action you will definitely know when it the ball is intentionally batted or kicked.

This is how I like to think about it as well, and further up Elvis did a great job of laying out the nuances of impetus.

When we have a loose ball here in a situation like OP described and a defensive player is coming in to address the ball, his actions will generally fall into one of two categories: either a) attempting to secure the ball himself, or b) attempting to bat/move the ball to prevent an opponent from securing the ball.  When any action that appears to be a) happens, this isn't impetus.  When the action is obviously b), it is.