Trial lawyers cannot sue drug manufacturers for defective warning labels on generics if labels were approved by the U.S. Food and Drug Administration, according to the U.S. Supreme Court. The 5-4 Pliva v. Mensing decision announced last week was a defeat for class-action trial lawyers hoping to profit on litigation based on allegations that manufacturers violated state laws that aren’t pre-empted by federal laws or regulations.

The Supremacy Clause of the Constitution requires that so long as a federal law is constitutional, it pre-empts divergent state laws.