violation or not?
 

A1 is making a inbounds pass, it deflects off A2 and goes in the back court is that a BC violation, when A2 starts dribble in the BC

No.

bummer i blew it but partner corrected me, and it had to be 2ot at that, whew thx

ofcourse not.
 

i think its obvious. but maybe i dont know the exact rule.

Explanation for NFHS (high school) rules:

There is no team control during the throw-in. The inbounds player did not catch the ball, which would have establised both player and team control, he merely touched it or had it touch him before going into the backcourt, where control was finally obtained. The backcourt provision takes effect only once control is gained, so there could not have been a violation prior to the ball first being held in the backcourt.

NFHS case book play 4.12.6(b) is the exact play. No violation.

buffalo,
As you have seen, this is not a violation at the NFHS level. Also, to clarify, the start of a dribble does not create make a play a BC violation (in situations in which the team was in control in the front court, thus creating a violation in the back court), it is simply the touch.

But the start of the dribble does constitute the beginning of both player and team control, which is the important moment of which to take note. No backcourt violation can occur prior to that moment.