The Dormant Commerce Clause, or Negative Commerce Clause, in American constitutional law, is a legal doctrine that courts in the United States have inferred from the Commerce Clause in Article I of the US Constitution. The primary focus of the doctrine is barring state protectionism. The Dormant Commerce Clause is used to prohibit state legislation that discriminates against, or unduly burdens, interstate or international commerce. Courts first determine whether a state regulation discriminates on its face against interstate commerce or whether it has the purpose or effect of discriminating against interstate commerce. If the statute is discriminatory, the state has the burden to justify both the local benefits flowing from the statute and to show the state has no other means of advancing the legitimate local purpose.

For example, it is lawful for Michigan to require food labels that specifically identify certain animal parts, if they are present in the product, because the state law applies to food produced in Michigan as well as food imported from other states and foreign countries; the state law would violate the Commerce Clause if it applied only to imported food or if it was otherwise found to favor domestic over imported products. Likewise, California law requires milk sold to contain a certain percentage of milk solids that federal law does not require, which is allowed under the Dormant Commerce Clause doctrine because California's stricter requirements apply equally to California-produced milk and imported milk and so does not discriminate against or inappropriately burden interstate commerce.

The doctrine was initially envisioned by Chief Justice John Marshall in the 1820s.