QB throws illegal pass that is caught, fumbled and recovered by defense what happens?
An illegal forward pass is treated like a legal pass until the down ends, so if the ball is caught by an offensive player, who subsequently fumbles it, the defense has a choice as to whether to decline the penalty and take the ball, or take the penalty, which is 5 yards and loss of down from the spot of the pass. In most cases, that would not be a smart option, since the ball would go back to the offensive team.
HOWEVER, if the illegal pass was thrown
on 4th down, the
defense MAY elect to accept the penalty. Why? Because the penalty for an IFP is 5 yards from the spot of the pass,
PLUS LOSS OF DOWN. So in that case, the defensive team may come out better by accepting the penalty, because they would take over possession 5 yards behind where the IFP was thrown from.
ON THE OTHER HAND let's say it was 4th down and 1 at the 50. The QB runs 7 yards past the line (to the +43) and throws a forward pass that is caught by an offensive teammate, who subsequently fumbles and the ball is recovered by the defense. In this case, the loss of down provision wouldn't make any difference, because it would still be a first down after the penalty was marked off. In that case, the defense would definitely decline the penalty and take the ball at the spot of recovery.