In 2001, the U. S. Congress passed Public Law 107-319 which exempts electric bicycles under 750 watts/20 mph from the definition of a motor vehicle only "For purposes of motor vehicle safety standards...", which means that the manufacturers of these bicycles don't have to meet federal equipment requirements, and are instead governed by the manufacturing requirements of the Consumer Product Safety Act. There is no mention of exemption from other federal, state, and local traffic laws, or exemption from the definition of a motor vehicle for other purposes.
Various states have passed their own laws. California law states that no driver's license, license plate, nor insurance is required. You must be 16 years or older and wear a standard bicycle helmet.
Electric bikes are subject to all the rules of the road, and additional laws governing the operation and safety of electric bicycles may be extended by state or local governments. It's legally a bicycle, so you can use it wherever and however you can use a bike - except on bicycle/pedestrian paths that are posted to prohibit "motorized bicycles".
(Efforts, however, are being made to change the California Vehicle Code to simplify the rules, reduce barriers, and fairly treat LEVs as viable transportation alternatives.)
Federal law trumps all States’ laws. That is true with bicycle law, too. States cannot constitutionally pass legislation that reduces or eliminates Federal laws, they can only pass legislation that enacts additional (tighter) restrictions on its people. This means that no State can enact legislation that allows wattages or speeds greater than the Federal Government’s limit of 750 Watts and a top electric-powered speed of 20 MPH. States can only legislate LOWER wattages and top-speeds (which, to our knowledge has not been done by any state).
An e-bike can go over 20 MPH, but not by means of the motor alone. In some states, bicycle speeds on public roads above 20 MPH cannot legally be motor-assisted. As a practical matter, police don't notice bikes going too fast.
If you live in a state that lacks basic electric bike legislation, consider this. Although riding your electric bike may be illegal, so is jay-walking. Generally speaking, 1) police don't know the exact rules, 2) police expect electric bike and scooter riders to wear a bicycle helmet, 3) most electric bikes look to the casual observer like ordinary bikes, and 4) if you get ticketed, just go to court and plead your case; judges usually let you off with a warning. And start working your state legislature to enact an electric bicycle law similar to California's.
Are there special insurance requirements?
No insurance is required to ride an e-bike. However, if you want to insure it against theft, check your current homeowner's insurance policy. An electric bicycle may be covered. To determine coverage, check with your insurance company or agent.
Is an electric bicycle considered a zero emission vehicle?
Yes. While some communities only define ZEV's as car replacements, others are looking for alternative ways to reduce sources of mobile pollution. Electric bikes have qualified for electric vehicle credits in some communities. Check with your local environmental management group for clarification. Every time you take a short trip on your electric bicycle rather than a car, you delete a cold start that would have added a significant amount of pollution.