City of Philadelphia v. New Jersey
437 U.S. 617 (1978)

• New Jersey law enacted a law that prohibited most "solid or liquid waste which originated or was collected outside the territorial limits" of New Jersey from being imported into the State.
• Philadelphia, as well as private landfill operators in New Jersey and several cities outside New Jersey sued on the basis that this was a ban on article of interstate commerce.
• New Jersey Supreme Court upheld the law on the grounds that it, "advanced vital health and environmental objectives with no economic discrimination against, and with little burden upon, interstate commerce."
• The US Supreme Court found the law unconstitutional.
• The Court found the law unconstitutional because it violated the Dormant Commerce Clause.
• Justice Stewart said, "whatever New Jersey's ultimate purpose, it may not be accomplished by discriminating against articles of commerce coming from outside the State unless there is some reason, apart from their origin, to treat them differently."
• In other words, New Jersey couldn't regulate beyond its borders.
• Furthermore, the Court held that legitimate local interests which had incidental interstate effects were within the State's general police powers, but protectionist legislation per se that is enacted by the State would be considered invalid.
• If New Jersey were to buy all the landfills, and then decide to only accept New Jersey wastes, under the market participation doctrine, that would be completely legal.