In the case of Mary Gade, Director, Illinois Environmental Protection Agency v. National Solid Wastes Management Association (1991), the U.S. Supreme Court ruled on whether states could impose stricter regulations than federal law regarding hazardous waste management under the Resource Conservation and Recovery Act (RCRA). The National Solid Wastes Management Association challenged an Illinois regulation that was more stringent than its federal counterpart. The court held in a 6-3 decision that while RCRA did not explicitly allow for stronger state standards, it also did not prohibit them. Therefore, states were free to enact their own laws as long as they were at least as protective of human health and environment as those set by federal law. This ruling affirmed states' rights to implement environmental protections beyond what is mandated federally.

In the dissenting opinion for the case of Mary Gade, Director, Illinois Environmental Protection Agency v. National Solid Wastes Management Association (1991), Justice Blackmun argued that federal law should not preempt state regulations unless it is clear that Congress intended this result. He believed that states should be allowed to enforce stricter environmental standards than those set by federal law if they choose to do so. According to him, preemption doctrine must be applied with caution and in a way consistent with both federalism principles and congressional intent. In his view, there was no evidence suggesting Congress intended to prevent states from imposing more stringent requirements on hazardous waste facilities when it enacted Resource Conservation and Recovery Act (RCRA). Therefore, he disagreed with the majority's decision which held Illinois' regulatory scheme as preempted by RCRA.