Legal Question in Civil Litigation in California

Re: Bringing food into movie theaters

It's not illegal in the sense that the police are not going to take you away in handcuffs. However, it is a violation of your license agreement to enter the theatre and watch the movie. The management would well within its rights to demand that you leave.

Re: Bringing food into movie theaters

Like any other owner or lessee of real estate, the theatre can set conditions on access to its premises. Provided these conditions don't conflict with the law they are binding on anyone who enters. There is no law against forbidding moviegoers to bring their own food, so the theatre's ban is legal and you can be ejected for violating it. If you are told to leave and refuse you become a trespasser and can be arrested.