In the case of Wisconsin et al. v. Minnesota Mining & Manufacturing Co., 1940, the U.S Supreme Court ruled in favor of Minnesota Mining and Manufacturing Company (3M). The State of Wisconsin had sought to tax 3M's income derived from interstate commerce activities, arguing that it was within its rights as a state to do so. However, the court held that such taxation would violate the Commerce Clause of the U.S Constitution which prohibits states from enacting laws or regulations that interfere with interstate commerce. This decision reaffirmed previous rulings by establishing clear limits on how far states could go in taxing businesses involved in interstate trade.

The dissenting opinion in the Wisconsin et al. v. Minnesota Mining & Manufacturing Co., 1940 case argued that the majority's decision to uphold a state tax on interstate commerce was inconsistent with previous rulings and threatened to disrupt national economic unity. The dissenters believed that this ruling would allow states to impose burdensome taxes on out-of-state companies, which could lead to retaliatory measures from other states and potentially harm nationwide business operations. They also pointed out that such taxation might discourage businesses from expanding their operations across state lines, thereby inhibiting economic growth and development at a national level.