The U.S. Supreme Court case Illinois v. Abbott & Associates, Inc., et al., 1982 revolved around the question of whether a state could regulate prices charged by wholesalers to retailers in order to prevent price discrimination that might harm competition. The State of Illinois had enacted legislation requiring milk distributors to charge grocers the same price they charged large volume buyers such as schools and hospitals, which typically received discounts due to their buying power. Milk distributors challenged this law under the Sherman Antitrust Act, arguing it was an illegal restraint on trade because it prevented them from offering competitive pricing based on volume sales. However, the Supreme Court ruled in favor of Illinois stating that Congress did not intend for federal antitrust laws (Sherman Act) to preempt state fair-trade laws aimed at preventing predatory pricing practices or other forms of anti-competitive behavior. The court held that states have authority under their general police powers to enact legislation protecting consumers and promoting fair competition even if such measures impact interstate commerce.

In the dissenting opinion for Illinois v. Abbott & Associates, Inc., Justice William Rehnquist argued that the majority's decision was inconsistent with previous rulings on state taxation of interstate commerce. He contended that the Court had previously upheld similar taxes and failed to provide a clear reason why this case should be treated differently. Furthermore, he criticized the majority's reliance on an economic analysis to determine whether or not discrimination against interstate commerce occurred, arguing it was outside their purview as judges to make such determinations. Instead, he believed these decisions should be left up to legislators who are better equipped to understand and respond appropriately to complex economic issues.