I know you're supposed to keep your ass on the bench while bench pressing. My friend consistently does not and was wondering if it is "illegal" to raise your ass up after the bar has touched your chest.
I googled it and from what I found it seemed to be, but thought I'd double check.
Any raising of the butt off the bench once you begin the lift is considering cheating and illegal in all PL federations. In worst case scenarios you can use an extra big belt or a tube and tie him down to the bench (or just take some weight off the bar).