When the Supreme Court soon decides South Dakota v. Wayfair, it will send a strong signal to all American consumers and taxpayers, especially small businesses. If South Dakota wins, all of us may confront tax demands from states and localities we’ve never visited and have nothing to do with. That’s because South Dakota wants to erase the court’s long-standing ‘nexus’ standard for demanding tax collections from out-of-state sellers.

Simply put, South Dakota wants to collect tax on all transactions with its residents, whether or not they involve out-of-state purchases. South Dakota says online sellers like Wayfair.com both deprive the state of “needed” revenues and get an unfair advantage over local sellers.