South Dakota v. Wayfair, Inc.

South Dakota v. Wayfair, Inc., 585 U.S. 162 (2018), was a United States Supreme Court case that held by a 5–4 majority that states may charge tax on purchases made from out-of-state sellers even if the seller does not have a physical presence in the taxing state. The decision overturned Quill Corp. v. North Dakota (1992), which had held that the Dormant Commerce Clause barred states from compelling retailers to collect sales or use taxes in connection with mail order or Internet sales made to their residents unless those retailers have a physical presence in the taxing state.

Since Quill in 1992, the volume of interstate sales via electronic channels, particularly purchases from Internet vendors, has grown rapidly, and the Government Accountability Office has estimated that in 2017, states had lost over US$13 billion in taxes that they could not collect. Following a statement made in a concurrence opinion by Justice Anthony Kennedy in a 2015 related case, which suggested that it was time to review the decision of Quill in the wake of modern technology, more than 20 states passed "kill Quill" legislation intending to collect sales tax from out-of-state vendors and did so purposely to provide the necessary legal vehicle to take to the Supreme Court. South Dakota was the first state to make its case through lower courts to the Supreme Court.

The Supreme Court granted a writ of certiorari in January 2018, heard the case on April 17, 2018, and issued its decision on June 21, 2018. A five-justice majority overturned Quill by ruling that the physical presence rule decided from Quill was "unsound and incorrect" in the current age of Internet services.