Pierce County, Washington v. Guillen

To encourage candid state reporting of dangerous roads for federal safety funding, Congress made materials collected under the Hazard Elimination Program non-discoverable in court proceedings; after Guillen's (plaintiff) wife was killed at a Pierce County, Washington (defendant) intersection previously flagged as hazardous, Guillen sought to introduce evidence of Washington's failure to fix the intersection in a wrongful-death suit. Washington moved to exclude that evidence under the federal discovery bar, and the Washington Supreme Court held Congress had exceeded its Commerce Clause power in enacting that bar; the U.S. Supreme Court granted certiorari.