California Motor Vehicle Code 21221
For the purpose of this code, the state of California defines motorized scooters as any self propelled two wheeled scooter designed to travel under 20 mph. The DMV definition is closer to what you would typically associate with a child's toy. If it has a place to stand, with or without a seat, and can also be powered by human propulsion, then it is probably a scooter. Mopeds also fall under motorized scooters for this code section.
Motorized scooters have the same rights and responsibilities as cars on California roads. If you are riding a scooter on the streets, think of it as if it were a motorized bicycle. Bicycle laws are very similar to the laws for scooters. Riders must have proper safety equipment and a fully functional vehicle to operate on public roads. Also, riders who are convicted of a DUI while riding on their scooters will receive the same $250 fine as car drivers and bicyclists. There are noise laws that apply to scooters and mopeds. If your scooter came with a muffler, it must work if you want to ride it in the city.
Scooter owners must have working brakes, lights and reflectors and other required safety equipment. Scooter owners are also required to wear helmets while riding on the streets. Anyone operating a motorized scooter or moped must be 16 years old before riding on a public street or in a park.
Scooter owners may not ride on the sidewalks or other areas where cars and bikes would not be allowed to operate. This is intended to keep both the scooter enthusiast and those around them safe. If a bike lane has been designated in your city, you should always ride your motorized scooter inside the designated lane.
The State of California encourages scooter and moped ownership. For this reason, most scooters do not have to be registered with the DMV. Scooter owners are also exempt from many of the financial responsibility laws that apply to car and truck owners.