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 carries the ball or imparts an impetus to it that forces it on, above, or

1
Impetus

• 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 carries the
  ball or imparts an impetus to it that forces it
  on, above, or across the goal line, or is
  responsible for a loose ball being on, above, or
  behind the goal line (RULE 8-7-1)
• Initial Impetus is imparted by a player who
  kicks, passes, snaps, or fumbles the ball shall
  be considered responsible for the balls progress
  in any direction even though its course is
  deflected or reversed after striking the ground
  or after touching an official or a player of
  either team.

2
Impetus

• Initial Impetus is considered expended and the
  responsibility for the balls progress is charged
  to a player
• If he kicks (intentionally) a ball not in player
  possession or bats (intentionally) a loose ball
  after it strikes the ground (Exception The
  original impetus is not changed when a loose ball
  is batted or kicked in the end zone).
• If the ball comes to rest but is not yet declared
  dead, and he gives it new impetus by any contact
  with it (Exception A ball at rest in the end
  zone or force touching).

3
Scrimmage kick
O
Touched by B
4
intercepted by B in the end zone
O
B is down
5
intercepted by B in the end zone and fumbles
O
B attempts to recover
6
A fumbles on 3rd down
O
B attempts to recover
B recovers
7
Hits Team B player on shoulder pad
Scrimmage Kick
o
Team A / Team B players attempt to recover
8
A fumbles on the 3 yard-line
O
B kicks/bats the ball out of end zone
9
A fumbles when ball is batted from hand by B
O
B recovers
10
Momentum

• The official should award the player the ball at
  the spot of the interception, catch, or recovery
• When an opponent
• Intercepts or catches a
• Forward pass
• Fumble
• Backward pass
• Scrimmage Kick or Free Kick,
• Recovers a
• Fumble
• Backward pass
• Scrimmage Kick or Free Kick
• Between his 5-yard line and the goal line,
• The runners original momentum carries him into
  the end zone where the ball is declared dead in
  his teams possession.

11
intercepted by B on the 3 yard-line
O
B is down
12
Free kick
O
Caught by B on 2 yard-line
B fumbles
13
Scrimmage kick
O
Caught by B
B fumbles _at_ 4 yard-line and A recovers