Who Should be Grounded??

So, yesterday I'm sitting at my desk working, Justin is in the garage cleaning his job materials out so that I can park in there (because our garage is a pit and we can't have ANY additional stuff in it without me losing my parking privileges). It was nasty and rainy so I was happy that I'd get to park in the garage after picking the kids up at Kelly's.
So I'm sitting, working and I hear a horrible - terrible- awful screeching sound - definitely not good.

I ran out to the garage to see my van in the driveway, touching the side of the garage door frame - not an inch away, or even an 1/8 of an inch away. Totally touching the side of the garage door frame. I freak a bit thinking that Justin passed out at the wheel or had a bad back spasm while pulling my van in.

NOPE. I look in and see Mason in the front seat, Justin in the back behind the driver's seat. HELLO!! Who let's a 13 year old pull a car into the garage that has a 1/2 inch of clearance on either side (never mind that he didn't even make it into the garage...) - when he's never, ever, EVER driven a car, touched a steering wheel or knows what a brake is?
Here's his skid mark on our rainy driveway:



So who should get grounded?
Mason? Justin?? or both?