Does the federal government enjoy plenary power to regulate every aspect of corporeal existence, down to the rodents living in your backyard? People for the Ethical Treatment of Property Owners (PETPO), an organization of concerned citizens from Utah, say no, and want the Supreme Court to hear them out. Article I of the Constitution lists the federal legislative powers: Congress may only act pursuant to one of these enumerated powers. One of these powers is the regulation of commerce “among the several states.” Starting with the New Deal, however, Congress has increasingly looked upon that power as a license to do whatever it likes. And for decades, the courts rubber‐stamped these increasingly expansive federal intrusions into areas traditionally reserved to the states. But in a series of cases, starting with 1995’s United States v. Lopez, the Supreme Court began to push back, reaffirming that federal regulation under the Commerce Clause must be, well, commercial. Recall that while Chief Justice John Roberts ultimately saved Obamacare by transmogrifying the individual mandate into a tax, he and the Court majority rejected the government’s arguments regarding the Commerce and Necessary and Proper Clauses. That brings us to the current case. The Utah prairie dog, which resides only within a small corner of southwest Utah, has no commercial value: there is no market for it—they make terrible pets—or any product made from it. Moreover, the current population is large and expanding. Yet it is listed as “threatened” under the federal Endangered Species Act. Its legal status derives from the distribution of its population: the government deems the 70% residing on private land a nullity, counting only the federal‐land population, on the theory that the citizens of Utah would declare open‐hunting on privately domiciled prairie dogs if the species were delisted. And, according to the U.S. Court of Appeals for the 10th Circuit, it doesn’t matter that the varmint is commercially worthless; other unrelated animals have commercial value, so the federal government can stick its nose into whichever animal it likes. Under this theory, of course, all organic life in the United States is subject to congressional whim, because some conjectural private party might impose some vaguely defined harm at some hypothetical future date. PETPO has filed a petition asking the Supreme Court to review the case. Cato, joined by the Reason Foundation and the Individual Rights Foundation, has filed an amicus brief urging the Court to grant review. At stake is not simply the beleaguered citizenry of Utah who wish to live their lives unmolested by pests—neither those living underground nor in the District of Columbia—but also the very system of enumerated powers that has protected the liberty of all Americans since the Founding.