That sucks man i hope it isn't to harsh but it's gotta be something to knock some sense into him because he's still technically not an adult until 18 and after that he will get fucked over 10 times harder. Watch him and make sure that if it keeps happening he gets help. When i was 15 is was caught over 5 times for DWI and driving without a license and I was never punish hard enough for it to help me but after I went to prison for attempted murder and a bunch of other shit I had my eyes knocked open and I got out of the gangs and I made something of myself. I hope he learns before he gets to the point where I was, I wish i did.