Stun guns are perfectly legal to own, possess and sell in California as long as they are not so powerful as to be lethal. Additionally, there are exceptions, including that you can't buy or use a stun gun if you are a minor under 16 without parental or legal guardian consent or have been convicted of a felony crime. Stun guns are weapons that use an electric shock to incapacitate a person. Taser is the most popular brand name manufacturer of stun guns, and California makes no distinction between the two.
TL;DR (Too Long; Didn't Read)
Stun gun ownership in California is entirely legal unless you have been convicted of misuse of a stun gun, a felony or any crime involving assault. Possession of a stun gun is also prohibited for those who are addicted to any narcotic drug and minors under the age of 16 who don't have parental or legal guardian consent.
Less Lethal Weapons
Stun guns are defined in section 244.5 of the California Penal Code as any offensive or defensive weapons capable of temporarily immobilizing a person by the infliction of an electrical charge. More generally, though, a stun is classified in the Penal Code as a less lethal weapon as long as it is designed to stun a person through the infliction physical pain or discomfort or the impairment of physical condition, function or senses to a degree that is not fatal.
Use by Law Enforcement and General Public
The California Penal Code expressly allows for peace officers and custodial officers to carry less lethal weapons, including Tasers and stun guns, for use in their official duties. It is generally legal for any resident, except for a felon, to possess a Taser or stun gun in California for legitimate self defense purposes, except for in public buildings and public meetings. Minors aged 16 and above can purchase, possess or use a Taser or stun gun with permission from a parent of legal guardian.
Sale of Stun Guns
It is legal to sell less-than-lethal Tasers and stun guns in California, subject to certain requirements and restriction. A stun gun must be sold with an instruction booklet and must possess a stamped or engraved manufacturer's serial number. Sale to a minor, except a minor over 16 years old and with parental consent, is a misdemeanor punishable by a fine of up to $1,000 and/or up to six months in imprisonment. It is also illegal to sell a Taser to anyone addicted to narcotics.
Assault with a Stun Gun
Any assault carried out with a stun gun is a punishable by up to a year in county jail or three years in state prison, depending on the severity and prior criminal history. Assault with a stun gun or Taser of a police officer or firefighter while in the course of their official duties is a more serious offense, punishable by up to a year in county jail or up to four years in state prison. Assault with a stun gun powerful enough to be considered a deadly is a more serious crime still that is punishable by up to four years imprisonment and or a fine of up to $10,000.