Federal Rules & Regulations
These are Federal regulations, which supersede any state law which is more stringent

Section 2085. Low-speed electric bicycles (a) Construction Notwithstanding any other provision of law, low-speed electric bicycles are consumer products within the meaning of section 2052(a)(1) of this title and shall be subject to the Commission regulations published at section 1500.18
(a)(12) and part 1512 of title 16, Code of Federal Regulations
(b) Definition For the purpose of this section, the term ''low-speed electric bicycle''
means a two- or three-wheeled vehicle with fully operable pedals and an electric motor of less than 750 watts (1 h.p.), whose maximum speed on a paved level surface, when powered solely by such a motor while ridden by an operator who weighs 170 pounds, is less than 20 mph.
(c) Promulgation of requirements To further protect the safety of consumers who ride low-speed electric bicycles, the Commission may promulgate new or amended requirements applicable to such vehicles as necessary and appropriate.
(d) Preemption his section shall supersede any State law or requirement with respect to low-speed electric bicycles to the extent that such State law or requirement is more stringent than the Federal law or requirements referred to in subsection (a) of this section.
A00071 Memo:
TITLE OF BILL: An act to amend the vehicle and traffic law, in relation to the definition of electric assisted bicycle
PURPOSE: This bill clarifies the vehicle and traffic law to define electric assisted bicycles; establish that electric assisted bicycles, as defined, are bicycles, not motor vehicles; and establish safety and operational criteria for their use.
SUMMARY OF PROVISIONS: Section 1 of the bill adds a new Section 102-c to the vehicle and traffic law, defining electric assisted bicycles as: A bicycle with two or three wheels which has a saddle and fully operative pedals for human propulsion, and also has an electric motor. However, the electric motor should not have a power output of more than one thousand watts, and should be incapable of propelling the a speed of more than twenty miles per hour on level ground. The electric motor should also be incapable of further increasing the speed of the device when human power alone is used to propel the device at or more than twenty miles per hour. Section 2 adds an exception in section 125 of the vehicle and traffic law to the statutory definition of motor vehicle for electric assisted bicycles.
Section 3 adds a new section 1240 to the vehicle and traffic law, the rules, regulations and provisions of the vehicle and traffic law applicable to bicycles applicable to electric assisted bicycles; makes the federal equipment and manufacturing requirements for bicycles or motor driven cycles applicable to electric assisted bicycles; and adds the following operational and safety requirements for electric assisted bicycles: electric motor disengagement criteria; all operators and passengers are required to wear bicycle helmets; and no-one under the age of 16 may operate or as a passenger on an electric assisted bicycle and establishes the civil fine and enforcement procedures for failure to wear a helmet. Section 4 is the effective date.
EXISTING LAW: None.
JUSTIFICATION: Defining and establishing operational criteria for electric assisted bicycles will clarify for authorities that these vehicles are more akin to bicycles than motorcycles. This will assist in interpreting the application of the appropriate vehicle and traffic laws to operators and passengers of these vehicles.

EFFECTIVE DATE: This act shall take effect immediately.

Rules and regulations regarding use of light electric vehicles vary from state to state. The information below is from the Federal, Maryland, DC, and Virginia governments. For more detailed information, contact the local officials in your area.

* National Highway Transportation Safety Administration: 49 CFR Part 571, [Docket No. NHTSA 98-3949], RIN 2127-AG58
PRECIS OF SUMMARY: (for full text of Summary, see 63 FR 33913). Responding to a growing public interest in using small 4-wheeled passenger vehicles to make short trips within retirement or other planned communities, NHTSA has issued Federal Motor Vehicle Safety Standard No. 500 Low-speed vehicles (LSV) based on its January 1997 proposal. Standard No. 500 requires basic safety equipment including lights, windshields windshield wipers, and seat belts on motor vehicles, other than trucks, whose maximum speed is between 20 and 25 miles per hour. The rule is effective June 17, 1998. The principal vehicle in this class is the Neighborhood Electric Vehicle (NEV). The rule does not apply to golf carts because their speed, as manufactured, is less than 20 mph. However, if any golf cart is modified on and after June 17, 1998, so that its maximum speed is over 20 mph, it must be conformed to Standard No. 500.
* Federal Highway Administration: TEA-21 Transportation Equity Act for the 21st Century - Public Law 105-178
Definitions [1202(a)(7)]
o Clarifies the permissibility of motorized wheelchair use on trails and pedestrian walkways that otherwise prohibit motorized use and also permits the use of electric bicycles on these facilities where State or local regulations permit.
o Electric bicycles are defined as any bicycle or tricycle with a low-powered electric motor weighing under 100 pounds, with a top motor-powered speed of 20 miles per hour.