Although it's usually a shame when someone gets arrested for weed, since usually there's no implications other than breaking a pathetic law that's opposed by 60% of the US population. In this case, the father got what he needed, this is a case where he should be arrested just to get it into his brain how dumb he is. First off, why was the weed in his son's backpack? Did he think it would look less suspicious walking out of a dark alley at 2am with an Elmo backpack? And the second issue is this, if you have something in your son's backpack that you think the school administration would disapprove of, then don't tell them. I can think of hundreds of times when I was in highschool with a bag of weed in my pocket, did I ever tell any of the staff? I graduated, so no. What he should've done is asked to see the kid, had the kid get the bag, then take a brown paper bag, put it into the backpack, put the weed into it, and pull it out. If anyone asks what he was doing, just say he gave his kid the wrong lunch bag.
See, if you're gonna break the law, you can't be an idiot. Smart people don't go to jail nearly as much as idiots. Smart people steal billions of dollars from banks and retreat to the Bahamas, dumb people smuggle weed in their kid's backpack and end up getting ass raped in jail.