For over a century, the Supreme Court has acknowledged and upheld Congress's power to overrule the Court's Dormant Commerce Clause decisions. In this Article, Professor Williams challenges the constitutionality of that practice, arguing that there is no more reason to allow Congress to overrule the Court's Dormant Commerce Clause decisions than its Equal Protection or First Amendment decisions. The Dormant Commerce Clause is not based on a statutory presumption of Congress's regulatory intent to leave certain fields free of state regulation, nor is it a limitation that exists merely for Congress's benefit, which therefore may be waived by Congress. Rather, the Dormant Commerce Clause is a constitutional limitation on state power that protects the ability of individuals to engage in commerce free of unduly burdensome or protectionist state regulation. At the same time, although Congress may not license state action that would otherwise violate the Dormant Commerce Clause, it still may cooperate with the states in ways such as incorporating otherwise valid state laws into federal regulatory programs.