California Code, Penal Code - PEN § 597g

(a) Poling a horse is a method of training horses to jump which consists of (1) forcing, persuading, or enticing a horse to jump in such manner that one or more of its legs will come in contact with an obstruction consisting of any kind of wire, or a pole, stick, rope or other object with brads, nails, tacks or other sharp points imbedded therein or attached thereto or (2) raising, throwing or moving a pole, stick, wire, rope or other object, against one or more of the legs of a horse while it is jumping an obstruction so that the horse, in either case, is induced to raise such leg or legs higher in order to clear the obstruction.  Tripping a horse is an act that consists of the use of any wire, pole, stick, rope, or other object or apparatus whatsoever to cause a horse to fall or lose its balance.  The poling or tripping of any horse is unlawful and any person violating the provisions of this section is guilty of a misdemeanor.

(b) It is a misdemeanor for any person to intentionally trip or fell an equine by the legs by any means whatsoever for the purposes of entertainment or sport.

(c) This section does not apply to the lawful laying down of a horse for medical or identification purposes, nor shall the section be construed as condemning or limiting any cultural or historical activities, except those prohibited herein.