What happens if B1 deflects A1's throw-in pass and it touches A1 while in flight out of bounds?

When B1 deflects A1's throw-in pass, and the ball subsequently touches A1 while in flight and goes out of bounds, the play is ruled as a situation where the ball is caused to go out of bounds by A1's own action. In this case, A1 is responsible for the ball's out-of-bounds status because they were the last player to touch it before it exits the court.

In high school basketball, if a player who is throwing the ball in has it touch them after being deflected by a defender and then goes out of bounds, that player's action directly leads to the ball going out of bounds. Therefore, the play results in the ball being deemed out of bounds as a direct consequence of A1's involvement. This highlights the rule that a player cannot be the last to touch the ball before it goes out and still have possession. The fundamental aspect here is that A1's touch while attempting to receive the ball constitutes the last touch before it goes out, placing the responsibility on them.