Mudslinger

Actually, I have a hard time believing he toked up right before the race cause if he did, his temper would have been mellowed to the point that he would have never gotten out of his car and "went off" on Stewart.
Come on people, use your heads, for anyone that has been around stoned folks, (not drunk AND stoned, just stoned), can anyone honestly recall a time where those stoned individuals got belligerent and violent?
That shit might give you the munchies, alter your way of thinking and make you stare at a spot on the wall for half an hour but I have never seen it make someone violent or increase their temper.
Really, it does quite the opposite. Do I think it was in his system from the day prior? Yep. Do I judge the kids character from the toxicology reports? No.
The kid made a bad decision on the track in the heat of the moment that cost him his life, I don't think Mary Jane had any influence on that decision at that time no matter what the toxicology report says. He's just one of many hot headed kids that unfortunately paid for a poor choice with his life.