The United States Supreme Court held that an unapportioned sales tax on the sale of tickets for interstate bus transportation services is not in violation of the "dormant" Commerce Clause of the United States Constitution.
Oklahoma Tax Commission v. Jefferson Lines, Inc., 115 S. Ct. 1331 (1995).
David J. Grecco,
Constitutional Law - Commerce Clause - State Taxation - Apportionment of Sales Taxes,
Duq. L. Rev.
Available at: https://dsc.duq.edu/dlr/vol34/iss1/8