California Code, Business and Professions Code - BPC § 18738

(a) A boxer who intentionally hits a contestant with a rabbit punch or with a punch on that part of the body over the kidneys shall be penalized by the loss of a point for each such punch.

(b) Determination that a boxer has violated this section shall be made at the end of the round in which the violation occurred and prior to the next round by the referee or, if judges are used in conjunction with the referee, by any two officials.  Upon such a determination, each such official shall penalize the boxer pursuant to subdivision (a).

(c) Upon a determination that this section has been violated, the referee shall inform both boxers and their managers at the end of the round in which the violation occurred and prior to the next round, and inform the audience of the penalty thus assessed.  In any such case, the rest period may be extended by the referee.