According to the Court, the "pertinent inquiry therefore is not how much commerce is involved but whether Congress could rationally conclude that the regulated activity affects interstate commerce".
If a state law does not discriminate against interstate commerce, they argue, the federal courts should not second-guess the state legislature about the balance between a statute's costs and benefits.
The court held that "to pass laws that arbitrarily burden interstate commerce, by forbidding shipments merely because they originate out of state, violates the Commerce Clause".
A state legislature that checks and constrains discrimination in interstate commerce.
Even when Congress has not acted, a state statute may run afoul of the dominant federal interest in the free flow of interstate commerce.
intrastate as well as interstate commerce.
Interstate Highway Commission; interstate highways; Interstate Commerce Commission; interstate commerce.