The law is called the Clean Air Act. It's a federal law so it covers all the US states (50).The Clean Air Act is a lengthy and complex federal law containing many provisions to improve and protect the outdoor air quality in the United States. It gives the U.S. Environmental Protection Authority (EPA) the responsibility for setting national ambient air quality standards to protect public health, while giving states the job of determining how best to meet those standards.

A Criteria Pollutant - Carbon Monoxide is produced primarily by motor vehicles. It can reduce a person's ability to think clearly, and causes visual impairment and headaches if high enough concentrations are experienced for a long period of time. Smoking vehicles, gasoline and diesel powered, which emit smoke from the exhaust pipe contribute to the degradation of ambient air quality.

see link: http://www.dep.state.fl.us/Air/programs/caa.htm

I agree that it is a vehicle that complies with the emission reguations of ALL 50 states in the USA.

When I was doing stuff for a famouse 2-letter car company, their emissions people had separated the world into three areas, CA (California), USA and RdW (Rest der Welt.

California's emission requirements were (at least back then) much tougher than any of the USA's other states, even with Federal regulations, amd VERY MUCH tougher than the rest of the world. Back then, Germans never even dreamed of a catalytic converter (yeah, I AM older than dirt!)