California Code, Penal Code - PEN § 537e

(a) Any person who knowingly buys, sells, receives, disposes of, conceals, or has in his or her possession any personal property from which the manufacturer's serial number, identification number, electronic serial number, or any other distinguishing number or identification mark has been removed, defaced, covered, altered, or destroyed, is guilty of a public offense, punishable as follows:

(b) For purposes of this subdivision, “personal property” includes, but is not limited to, the following:

(c) When property described in subdivision (a) comes into the custody of a peace officer it shall become subject to the provision of Chapter 12 (commencing with Section 1407) of Title 10 of Part 2, relating to the disposal of stolen or embezzled property. Property subject to this section shall be considered stolen or embezzled property for the purposes of that chapter, and prior to being disposed of, shall have an identification mark imbedded or engraved in, or permanently affixed to it.

(d) This section does not apply to those cases or instances where any of the changes or alterations enumerated in subdivision (a) have been customarily made or done as an established practice in the ordinary and regular conduct of business, by the original manufacturer, or by his or her duly appointed direct representative, or under specific authorization from the original manufacturer.