On August 16, 2018, the Multistate Tax Commission and Federation of Tax Administrators jointly filed an amicus brief in the U.S. Supreme Court in Washington v. Cougar Den. On its surface, the case concerns the rules of construction applicable to Native American treaties. But the MTC and FTA filed this brief to emphasize the potential effect an adverse decision could have on state fuel and tobacco taxes. The amici explained the interconnected nature of the administration and enforcement of many state taxes and requested greater clarity from the Supreme Court about the treaty provision at issue. You can read the brief by clicking here .