Illegal forward pass on 4th down

[JugglingReferee]

Originally Posted by wyo-referee

A1 is running for the goal line on 4th down, as he's getting tackled he throws the ball forward from the 3 yd. line and A2 catches it in the endzone.
B has to take the penalty to keep the score from happening. So is it 1st and 10 from the 8 for team B?

CANADIAN RULING:

If it's possible that the ball carrier thought he was behind the line of scrimmage, but was beyond the line of scrimmage, enforce as an illegal forward pass. 10 yards from the PLS, repeat the down.

Otherwise, enforce as an offside pass subject to penalty. Downs continue at the spot of forward pass. Note that this is a "violation", and not a foul, therefore Team A (or B if yards were not gained) does not get one more play should time expire during this play. Since it was 4th down, we need to look to see if yards were gained at the 3 yard line. If so, A gets a new series; and if not, it is B's ball providing that time did not expire during the play.