If Congress imposes a regulation on an industry that has a limiting effect, the Supreme Court has held that, in general:

a. Congress may burden interstate commerce, but states may not do so unless authorized by Congress

b. States may then imitate the regulation at the state level

c. Congress may not impose regulations that burden foreign firms doing business in the U.S.

d. Congress may not regulate intrastate commerce, if the effect is "inherently uncompetitive"

e. Congress may regulate commerce only with approval of the affected states