CALIFORNIA MOTORCYCLE HELMET LAW: How can I know that my motorcycle helmet meets compliance standards under the California Helmet law?

Here is a good rule of thumb:  When you are shopping for a good motorcycle helmet, or if you have one already in your possession, look for a Department of Transportation label on the helmet (it will read "DOT"), which is the manufacturer's certification that the helmet conforms to federal safety standards.  The state of California will acknowledge the minimal federal safety standards with all motorcycle helmets in the state.   You will know that you have met the minimal safety standards to comply with the California law.