The U.S. Supreme Court case Spector Motor Service, Inc. v. McLaughlin involved a dispute over state taxation of interstate commerce activities. The plaintiff, Spector Motor Service, was an interstate motor carrier operating under the authority of the Interstate Commerce Commission and paid taxes to multiple states for its operations across state lines. Connecticut's tax commissioner sought to impose a franchise tax on Spector for doing business in the state which led to this litigation. Spector argued that such taxation violated the Commerce Clause of the Constitution by placing undue burden on interstate commerce activities as it was already paying similar taxes in other states where it operated. In 1944, The Supreme Court ruled in favor of Spector stating that Connecticut’s imposition of a franchise tax solely because they were engaged in interstate commerce constituted discrimination against said commerce and thus contravened with constitutional principles laid out by Congress regarding regulation and control over such matters.

The dissenting opinion in the Spector Motor Service, Inc. v. McLaughlin case argued that Connecticut's tax on the gross earnings of foreign corporations was not discriminatory and did not violate the Commerce Clause of the U.S Constitution. The dissenters believed that this tax was a fair means for states to share in revenue from interstate commerce activities occurring within their borders, especially when such businesses used state resources or infrastructure but were otherwise exempt from local property taxes due to their interstate nature. They also pointed out that similar taxes had been upheld by previous court rulings and saw no reason why this particular instance should be treated differently. Furthermore, they disagreed with majority’s view about “doing business” as being synonymous with engaging in interstate commerce; instead they viewed it as a broader term encompassing all corporate activities within a state’s jurisdiction including those which are purely local or intrastate.