I just saw a weird holding penalty. The pass was completed for a 10 yd gain and I am guessing that the hold also happened 10 yds down field. Regardless the spot of the hold the next play should have been first down and 20 from the 10 yrd line but instead it was 1st down and 10 from the original line of scrimage. These spot fouls for holds really should only come into play on special teams or if it happens in end zone.

Original play:
1-10-CHI 20 (5:33) 13-Christopher Allen pass complete to 45-Alfred Howard to CHI 30 for 10 yards. Tackle by 29-Mike Anderson. PENALTY - Holding (CHI 80-Dan Grant)

Next Play:
1-10-CHI 20 (5:29) 13-Christopher Allen pass complete to 80-Dan Grant to CHI 37 for 18 yards. Tackle by 39-Brian Garcia.

again same game except this time the offense actually was rewarded 5 yds because of spot of hold

1-10-CHI 1 (13:18) 45-Alfred Howard ran to CHI 19 for 18 yards. Tackle by 24-Roy Bates. TBY 79-Raymond Green was injured on the play. PENALTY - Holding (CHI 65-Ernesto Burns)

1-5-CHI 5 (13:12) 13-Christopher Allen pass complete to 80-Dan Grant to CHI 13 for 8 yards. Tackle by 39-Brian Garcia.

This is my understanding.

If holding occurs behind the line of scrimmage, the penalty is enforced from the line of scrimmage. If it occurs beyond the line of scrimmage, it is enforced from the spot of the foul.

It appears to me as if both plays were correct.

Actually I think only one of them is correct. If it is a run play then it is spot of foul. If it is a pass play then the pass is negated and ball is spotted at original line of scrimmage and penalty marked from there. It may be different if the hold happens after the completion. That I am not sure of.

You're right. I should have mentioned that I was assuming the holding occurred after the catch was made.

Which league did this happen in? The logic should be correct in that the spot of the foul should determine where the penalty is marked off from (or the LOS if the penalty occurred behind the LOS), and there should not be a downfield hold until after the pass has been caught, but I can look to make sure something strange didn't happen. You can also see when the holding occurred by seeing when the "Penalty" indicator appears while watching the playback.

It happened in MFN2

I looked up the NFL rules on spot of foul and these are correct. It is just funny because I cant recall ever seeing it happen in the NFL. I actually remember a play last season the Julien Edelman caught WR screen pass and was going down the side and Gronk got called for a hold some 20 yards down field before Edeleman was finally knocked out of bounds around 10 yd line and the play was called all the way back to the line of scrimmage and then penalty added.