California generally prohibits people from possessing, knowingly transporting, selling, offering to sell, or knowingly manufacturing a machine gun without a permit.¹ California also prohibits intentionally converting a firearm into a machine gun.² The definition of “machine gun” in California law is identical to the definition in federal law and means “any weapon that shoots, is designed to shoot, or can readily be restored to shoot, automatically more than one shot, without manual reloading, by a single function of the trigger.”³ The term also includes any weapon deemed by the federal Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) as “readily convertible” to a machine gun.⁴

California was also one of the first states to prohibit the sale, manufacture, and possession of bump stock devices and other “multi burst trigger activators,” which are firearm accessories designed to significantly increase the rate of fire of a semi-automatic firearm to simulate automatic machine gun fire.⁵ In 2018, California passed new legislation to clarify and broaden this prohibition on bump stocks and similar devices, to include devices that are designed to be attached to, built into, or used in conjunction with, a semiautomatic firearm.⁶

The California Department of Justice (“DOJ”) may issue permits to individuals who are 18 years of age or older for the possession, manufacture, or transportation of machine guns, only upon a satisfactory showing of good cause.⁷ The permit must be kept where the firearms are kept, and the permit must be open to inspection by law enforcement.⁸ DOJ may also grant licenses effective for not more than one year for the sale of machine guns to persons authorized to receive them under state law.⁹ A similar permit may be issued by DOJ to allow for the manufacture, possession, importation, transportation, or sale of short-barreled rifles or short-barreled shotguns.¹⁰

California law makes it a nuisance to possess a machine gun not in compliance with the above requirements.¹¹ The Attorney General, any district attorney, or any city attorney may bring an action before the superior court to enjoin the possession of any illegally possessed machine gun.¹² Any illegally possessed machine gun must be surrendered to DOJ, and DOJ will destroy it, unless a judge or district attorney files a statement with DOJ stating that its preservation is necessary to serve the ends of justice.¹³

Federal law requires machine guns to be registered with the Bureau of Alcohol, Tobacco, Firearms & Explosives (ATF), and generally prohibits the transfer or possession of machine guns manufactured after May 19, 1986.¹⁴

1. Cal. Penal Code § 32625(a).[↩]
2. Cal. Penal Code § 32625(b).[↩]
3. Cal. Penal Code § 16880(a).[↩]
4. Cal. Penal Code § 16880(c). The definition of machine gun also includes any part designed and intended solely and exclusively, or combination of parts designed and intended, for use in converting a weapon into a machine gun, and any combination of parts from which a machine gun can be assembled if those parts are in the possession or under the control of a person. Cal. Penal Code § 16880(b).[↩]
5. Cal. Penal Code §§ 16930, 32900. In October 2017, a gunman in Las Vegas used multiple bump fire devices to convert semi-automatic rifles into weapons that fired 9 shots per second. He used those weapons to carry out the deadliest mass shooting attack in modern history.[↩]
6. See 2018 CA SB 1346, amending Cal. Penal Code § 16930.[↩]
7. Cal. Penal Code § 32650.[↩]
8. Cal. Penal Code § 32660.[↩]
9. Cal. Penal Code § 32700.[↩]
10. Cal. Penal Code § 33300.[↩]
11. Cal. Penal Code § 32750(a).[↩]
12. Cal. Penal Code § 32750(b).[↩]
13. Cal. Penal Code § 32750(c).[↩]
14. 18 U.S.C. § 922(o); 26 U.S.C. § 5861(d).[↩]