Try this one

[sportswriter]

> 4th and 15 from a team's own 5 yard line.
> Punter is in the EZ. Snap comes and the P fumbles the
> catch, the ball drops to the ground, in the EZ.
> [... punter hoofs ball...]Now, the ball hits a member of
>the defence (receiving team if you will) at the 3 yard
> line (by accident - through no purpose of his own),
> then bounces back into the EZ. The P and a member of the
> receiving team both jump on the ball at the same time.

Geeez, you've got a real brain-stumper here!

Dunno how the four-down ruling would go, but my scan on it (being a Canuck) would work on the following principles:

In Canadian ball, a "simultaneous possession" goes to the team that originally had possession. Since the ball did not cross the line of scrimmage, the kicker has not yet surrendered posession (ie: if they could recover the ball, they could opt for a forward pass, etc, etc.)

Therefore, the ball at the end of the play belongs to A - still. However.... since yards were not gained, the ruling would be a safety touch.

(In Canadian ball, B could also opt to scrimmage from the 5 yard line, because the blocked kick went into the enzone on a third [kicking] down.)