Also, I believe it's a federal requirement that all motor vehicles must have functioning emergency/parking brakes. There may be others, but for example under:
FEDERAL
MOTOR VEHICLE
SAFETY STANDARDS
AND REGULATIONS
U.S. DEPARTMENT OF TRANSPORTATION
NATIONAL HIGHWAY TRAFFIC
SAFETY ADMINISTRATION
Standard No. 105 - Hydraulic and Electric Brake Systems - Passenger Cars (Effective 1-1-68)
This standard specifies requirements for vehicles equipped with hydraulic and electric service brake systems and associated parking brake systems to ensure safe braking performance under normal conditions and emergency conditions.
