Reaching out of your area

[ilyazhito]

That contact was not incidental to an attempt to play the ball. It was illegal contact to a shooter's arm, obviously below the wrist.

If the defender was vertical and just happened to make contact with the shooter's hand/arm, I would have let it go, but the defender struck the shooter on the arm without striking the ball. The rule of thumb is contact to ball + body = play on, but contact to body + ball = foul. In this case, there was contact to body without contact to the ball, and the contact was illegal.