Just a few short years after the federal government eliminated Amazon’s most formidable competition in book sales, Washington is now helping the tech giant prevent upstarts from challenging its position in electronic commerce.
Years from now Thursday’s 5-4 Wayfair decision allowing state and local governments to force out-of-state retailers to collect taxes will be the one that Clarence Thomas, Samuel Alito and Neil Gorsuch regret the most. The other two Justices in support, Ruth Bader Ginsburg and Anthony Kennedy, will likely...