This Article asserts that states may invoke the Supreme Court’s original jurisdiction to challenge marijuana legalization in Colorado. The State’s introduction of marijuana into interstate commerce has reawakened a long-dormant body of constitutional law dealing with transboundary nuisance disputes between states. In making this argument, we distinguish our theory from the complaint lodged by Nebraska and Oklahoma with the Supreme Court. Nebraska and Oklahoma seek to enforce the Supremacy Clause of the U.S. Constitution, contending that Colorado’s venture violates the federal Controlled Substances Act. In contrast, we assert that the Court should award damages to a prevailing state, using the Coase Theorem of market efficiency as its guide. Real-world application of this Theorem can be attained by imposing a legal rule charging the nuisance with the damages it causes. If compelling a polluter to internalize the cost of its pollution drives it out of business, then the enterprise was not the most economically efficient use of the property. In contrast, if the polluter assumes responsibility for all the costs of the venture and still realizes a sufficient profit to stay in business, then its use of the land is most efficient. If this remedy is applied, the market will determine the success or failure of Colorado’s venture and will serve as a guide to other states in deciding whether it is worth emulating.