Six online retailers recently sued the Massachusetts Department of Revenue over the pre-Wayfair enforcement of regulation 830 CMR 64H.1.7 (“Remote Sales Tax Regulation”). The complaint argues that, prior to the Supreme Court’s decision in South Dakota v. Wayfair, Inc., No. 17-494 (U.S. Jun. 21, 2018), the Remote Sales Tax Regulation violated the Due Process Clause of the U.S. Constitution and the Internet Tax Freedom Act. On Due Process, the six online retailers argue the Remote Sales Tax Regulation places an undue burden on, and discriminates against, interstate commerce. The online retailers also argue that the Remote Sales Tax Regulation violates the Internet Tax Freedom Act’s prohibition of discriminatory taxes on electronic commerce.