Here is what California says about Pocket Bikes:
New 2006 California Pocket Bike Law:
New 2006 California Vehicle Code §21720 makes it illegal to operate a pocket bike on a sidewalk, roadway, or any other part of a highway, or on a bikeway, bicycle path or trail, equestrian trail, hiking or recreational trail, or on public lands open to off-highway motor vehicle use. This new law requires the manufacturer to provide a disclosure statement to the buyer which clearly indicates where a pocket bike cannot be operated and authorizes law enforcement to seize a pocket bike and hold it for 48 hours when the operator is cited for violation of Vehicle Code §21720
I would advise anyone thinking of buying a Pocket Bike to find out what the law is in your state.