One of the liberties protected by the Constitution is the right to do business in other states, on the same terms as companies based in those states. That right is enshrined in the Privileges and Immunities Clause of Article IV, section 2, one of the handful of individual rights that the Framers saw fit to safeguard even before the Bill of Rights was enacted. In fact, ensuring the opportunity to do business out‐of‐state on equal terms with a state’s residents was one of the principal motivations for holding the Constitutional Convention in the first place. But the U.S. Court of Appeals for the Ninth Circuit has condoned California’s violation of that right. California enacted a set of commercial‐fishing license fees that require nonresidents to pay several times more than residents. The system is explicitly discriminatory, harshly regressive, and intentionally protectionist. The Supreme Court and the Fourth Circuit, in substantively identical circumstances, have ruled these kinds of provisions to be impermissible: States must charge license fees equally to residents and nonresidents alike, or else bear the burden of justifying their discrimination (which California has made little real effort to do). But an en banc majority of the Ninth Circuit quite literally imposed the opposite rule. Not only did it uphold California’s discrimination, but it supported its holding with guesstimates of tax payments and rough calculations of economic costs that the state itself had never supplied. The result is conflict between two federal circuits, and an open door for new methods of discrimination that the Constitution has always forbidden. Now, a group of fishermen, with amicus support from Cato, is asking the Supreme Court to hear their case and strike down California’s differential commercial fishing license fees. Under the Ninth Circuit’s reasoning, everything California spends on fishery regulation is considered a “subsidy” to that industry—a subsidy paid by resident taxpayers for which the state must be compensated. This framing ignores the fact that nonresident fishermen also pay California sales tax and California income tax for income derived from in‐state activities (when their income is enough to qualify for taxation, which it often isn’t) and directly contradicts controlling Supreme Court precedent. This dangerous rationale could otherwise be applied to any number of the nearly one‐third of US occupations currently regulated by the states, and if unchecked could contribute significantly to creating just the sort of balkanized national economy that the Constitution was intended to prevent. The fact of the matter is that California is attempting to protect local business interests at the expense of nonresidents and dress up its blatantly protectionist violation of the Privileges and Immunities Clause in reasonable‐sounding language about fairness. The Supreme Court should grant certiorari and remind the Ninth Circuit that this sort of behavior is constitutionally unacceptable.