262 U.S. 553 (1923)
Pennsylvania v. West Virginia is a landmark Supreme Court case that addressed the issues of state sovereignty, interstate commerce, and environmental law in the early 20th century.
Does a state statute that requires local natural gas companies to prioritize in-state users before exporting impede interstate commerce and violate the Commerce Clause?
A state may not enact legislation that unduly burdens interstate commerce or discriminates against out-of-state economic interests, according to the Dormant Commerce Clause doctrine.
The Supreme Court held that the West Virginia statute discriminated against interstate commerce by giving preference to in-state customers for natural gas, and thereby violated the Commerce Clause.
Pennsylvania v. West Virginia is pivotal for its articulation of the limits of state power under the Commerce Clause. It underscores the principle that while states can control local matters, their regulations must not interfere with the broader national market and must respect the interests of other states. This decision is particularly relevant for law students studying the balance of power between state and federal authority, as well as the development of environmental law where interstate impacts are prominent.