4th down change of possession

[JugglingReferee]

Originally Posted by phansen

Casebook 5.3.3 discusses how the ball is placed after 4th down and a change in possession. From what I understand the ball is placed as it was prior to the 4th down play on a pass. On a run the foremost point of the ball now becomes the rear point of the ball for the new offensive team. The line-to-gain chains would move accordingly to the foremost point of the ball in the new direction.

Is this correct? Or am I missing something?

So then in the US, the LS actually changes on a 4th-down incomplete pass?

Play: The tip of the football is at centre-ice: right in the middle of the 50 yard stripe (equidistant from both goallines). On 4th down, A throws an incomplete pass. (Let's say that the ball is 10 inches in length, therefore the back tip is at the 49 yard, 26 inch line.)

Ruling: When B takes over on downs, is the tip of the ball for forward progress now the 49 yard, 26 inch line, or does it remain, as it should, at the 50 yard line?