Cal. Pen. Code § 597p
Within 30 days after the passage of this act, every owner, or user of any docked horse, within the State of California, shall register his or her docked horse, or horses by filing in the office of the county clerk of the county in which such docked horse, or horses, may then be kept, a certificate, which certificate shall contain the name, or names of the owner, together with his or her post office address, a full description of the color, age, size and the use made of such docked horse, or horses; which certificate shall be signed by the owner, or his, or her agent. The county clerk shall number such certificate consecutively and record the name in a book, or register to be kept for that purpose only; and shall receive as a fee for recording of such certificate, the sum of fifty cents ($0.50), and the clerk shall thereupon issue to such person so registering such horse or horses a certificate containing the facts recited in this section which upon demand shall be exhibited to any peace officer, and the same shall be conclusive evidence of a compliance with the provisions of Section 597n of this code.
Ca. Pen. Code § 597p