In Hughes v. Oklahoma, the U.S. Supreme Court ruled that an Oklahoma statute prohibiting the sale of minnows caught within the state to out-of-state buyers was unconstitutional because it violated the Commerce Clause of the Constitution. The court held that states cannot discriminate against interstate commerce unless there is a valid reason related to local interest and no non-discriminatory alternatives are available. In this case, while conservation of natural resources could be considered a legitimate local concern, Oklahoma failed to demonstrate why less discriminatory means would not adequately protect their interests in conserving wild minnow populations. Therefore, despite acknowledging states' rights over wildlife within their borders under common law principles (the "wildlife exception"), they concluded these rights do not supersede federal authority over interstate commerce.

In the dissenting opinion for Hughes v. Oklahoma, Justice Rehnquist disagreed with the majority's decision to strike down an Oklahoma law prohibiting out-of-state transportation of minnows caught within its borders. He argued that this case was not about commerce but wildlife conservation and states should have a right to conserve their natural resources without interference from Congress or courts. He believed that the Court had overstepped its bounds by invalidating state laws based on what it perceived as national interests, rather than deferring to states' rights in matters concerning local affairs and industries. Furthermore, he contended that there was no evidence showing this law discriminated against interstate commerce since it applied equally to both residents and non-residents alike; thus, it did not violate the Commerce Clause of Constitution.