A bit of background info:
Direct link to bill info on CA's state government site
Current law in CA already places restrictions on imitation firearms. It's illegal to modify them to make them look more realistic, it's illegal to open-carry them in public, etc. This means to you: If you're using replica guns to shoot a home movie, you better not be running down public streets waving those things around, because that would be illegal and you will probably be detained and arrested or fined. Airsoft and Paintball currently fall under the "BB Devices" category. BB Devices are not considered imitation firearms and are subject to a different set of regulations that are slightly more relaxed.
This law was proposed after an incident where a kid was shot by a police officer after drawing a BB gun: Dr. Airsoft blog article(and LA Times original article )
Their perceived need for the bill is based on an event that was reported in December, 2010, in the Los Angeles Times. The story was about a 13-year-old Glassell Park boy who was shot and injured by a Los Angele Police Department officer. Officer Victor Abarca shot the boy, thinking that the boy was producing a real gun when ordered to surrender. According to the LA Times article, Lt. John Romero, police spokesman, "said the youth pulled the gun from his clothing in a motion consistent with drawing a weapon." It also said that the event occured after 7:50 PM in December, and that the officer was shining a flashlight on the boy.
Why you should care about this proposal:
Milsim markers may not look like real firearms to you or me, especially with the massive hopper on top and air tank in back. Unfortunately for us the subjective judgment relies on the subjective judgment of a "reasonable person" to decide whether or not THEY think it is. That person will most likely be a police officer who's deciding whether or not to give you a ticket. In addition to the subjective judgment affecting people in CA directly, it will have a chilling effect on the sale, distribution or even transportation of milsim markers THROUGH California so if a company has their gear made overseas in the UK or in China, and is imported to the USA through California's majority of west-coast shipping docks, the importer is liable to be fined by CA law enforcement.