Article I, Section 8, Clause 3:
[The Congress shall have Power . . .] To regulate Commerce with foreign Nations, and among the several States, and with the Indian Tribes; . . .
Transition from the old law to the modern standard occurred relatively smoothly in the field of regulation, 1 but in the area of taxation the passage was choppy and often witnessed retreats and advances. 2 In any event, both taxation and regulation now are evaluated under a judicial balancing formula comparing the burden on interstate commerce with the importance of the state interest, save for discriminatory state action that cannot be justified at all.