Justice Anthony Kennedy’s majority opinion in the online-sales-tax case South Dakota v. Wayfair was his final — and most significant — decision involving the dormant commerce clause doctrine, which prohibits state and local governments from passing laws that discriminate against or unduly burden interstate commerce unless Congress consents. Wayfair also was a sharp break from Kennedy’s dormant commerce clause jurisprudence over the preceding three decades. Before Wayfair, Kennedy was one of the most ardent defenders of the much-maligned dormant commerce clause and one of the most reliable votes in favor of litigants who challenged state and local laws on the ground that they violated that doctrine. Wayfair, in which the majority overturned decades-old precedents that had prohibited states from collecting sales taxes on their residents’ transactions with out-of-state online and mail-order retailers, was a rare dormant commerce clause case in which Kennedy cast a decisive vote on the states’ side.

Although Wayfair was in many ways uncharacteristic of Kennedy’s dormant commerce clause jurisprudence, his jurisprudence in this area was emblematic of his larger body of opinions and votes. First, Kennedy was a faint-hearted federalist. While his rhetoric regarding federalism was lofty, his votes in concrete cases often did not match up. His most influential dormant commerce clause opinions prior to Wayfair included C & A Carbone Inc. v. Town of Clarkstown, in which he wrote for a five-justice majority to strike down a municipal ordinance that required solid waste generated within the town’s boundaries to be deposited at a designated processing facility, and Granholm v. Heald, in which he wrote for a 5-4 majority invalidating state laws that limited the ability of out-of-state wineries to sell directly to consumers. He also cast a crucial fifth vote to strike down a Maryland personal-income-tax law on the basis of the dormant commerce clause in Comptroller v. Wynne, and dissented from several majority opinions upholding state laws challenged on dormant commerce clause grounds.

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