The Constitution did not define the phrase “among the several states.” That task was left to the courts. Gibbons v. Ogden  was the first major case construing
the Commerce Clause.
Congress has plenary (“complete in itself”) power to regulate commerce.
Modern Test for validity of state statutes that affect interstate commerce:
1.    The regulation pursues a legitimate state end.
2.    The regulation is rationally related to the legitimate end
3.    The regulatory burden imposed by the state on interstate commerce and any
discrimination against interstate commerce must be outweighed by the state’s
interest in enforcing the regulation. Balancing and proportionality.
Commerce Clause reaches into three main categories of problems:
Three (3) categories for Congress to exercise power over commerce
1.    channels
2.    instrumentalities
3.    activities affecting commerce.
The Test for Validating/Invalidating Statutes Affecting Commerce
1.    Does the statute have a Legitimate End
2.    Is the statute Rationally Related to the legitimate end
3.    Does the statute strike a Balance between the Burden it imposes and its
Aim