More than fifty years ago, in 1967, before there was an Internet, the U.S. Supreme Court held that the states could not impose on out-of-state mail-order sellers the obligation to collect and remit sales taxes for sales made to customers in states where those sellers had no stores, warehouses, or other physical presence. In striking down an Illinois law that imposed collection obligations on such remote sellers, the Court held that both the dormant Commerce Clause and the Due Process Clause prohibit the states from taxing remote sellers without a physical presence within the state. A quarter century later, in 1992, the Court had a chance to reconsider its earlier ruling in a case called Quill v. North Dakota. The Quill Court reiterated its...