The U.S. Supreme Court case Sage Stores Co. et al. v. Kansas ex rel Mitchell, 1944, involved a dispute over the state of Kansas's right to regulate retail prices under its Fair Trade Act during World War II era price controls set by the federal government’s Office of Price Administration (OPA). The plaintiffs were retailers who sold products at lower than minimum prices established by manufacturers and challenged the constitutionality of such regulation arguing it conflicted with federal law which allowed them to sell goods at lower prices due to OPA regulations. The court ruled in favor of Kansas stating that there was no conflict between state and federal laws as both aimed at preventing unfair competition and maintaining market stability.

The dissenting opinion in the Sage Stores Co. v. Kansas case argued that the state of Kansas had overstepped its bounds by imposing a tax on out-of-state retailers who sold goods to customers within the state, even if those sales were conducted through catalogs or other forms of indirect commerce. The dissenters believed this was an unconstitutional interference with interstate commerce and violated principles of federalism, as it allowed states to regulate and tax activities beyond their borders. They contended that such taxation could lead to economic protectionism and disrupt national unity by encouraging states to enact laws favoring local businesses at the expense of out-of-state competitors.