2009 California Penal Code - Section 12500-12501 :: Article 1. General Provisions

12500.  The term "silencer" as used in this chapter means any device
or attachment of any kind designed, used, or intended for use in
silencing, diminishing, or muffling the report of a firearm. The term
"silencer" also includes any combination of parts, designed or
redesigned, and intended for use in assembling a silencer or
fabricating a silencer and any part intended only for use in such
assembly or fabrication.

12501.  Section 12520 shall not apply to, or affect, any of the
following:
   (a) The sale to, purchase by, or possession of silencers by
agencies listed in Section 830.1, or the military or naval forces of
this state or of the United States for use in the discharge of their
official duties.
   (b) The possession of silencers by regular, salaried, full-time
peace officers who are employed by an agency listed in Section 830.1,
or by the military or naval forces of this state or of the United
States when on duty and when the use of silencers is authorized by
the agency and is within the course and scope of their duties.
   (c) The manufacture, possession, transportation, or sale or other
transfer of silencers to an entity described in subdivision (a) by
dealers or manufacturers registered under Chapter 53 (commencing with
Section 5801) of Title 26 of the United States Code, and the
regulations issued pursuant thereto.