To address the increased risk of liability for accidents that took place at hazardous locations before improvements could be made Congress adopted 23 U. S. C. §409, which provided: 'Notwithstanding any other provision of law, reports, surveys, schedules, lists, or data compiled for the purpose of identifying[,] evaluating, or planning the safety enhancement of potential accident sites, hazardous roadway conditions, or railway-highway crossings, pursuant to sections 130, 144, and 152 of this title or for the purpose of developing any highway safety construction improvement project which may be implemented utilizing Federal-aid highway funds shall not be admitted into evidence in Federal or State court or considered for other purposes in any action for damages arising from any occurrence at a location mentioned or addressed in such reports, surveys, schedules, lists, or data.' Surface Transportation and Uniform Relocation Assistance Act of 1987, §132, 101 Stat. 170. Some courts held that §409 addressed only the admissibility of relevant documents at trial and did not apply to pretrial discovery. The information would be inadmissible at trial; it nevertheless remained subject to discovery. Others contend that §409 protected only materials actually generated by a governmental agency for §152 purposes, and documents collected by that agency to prepare its §152 funding application remained both admissible and discoverable. In 1991, Congress expressly made the statute applicable to pretrial discovery, and in 1995, Congress added the phrase 'or collected' after the word 'compiled.' Ignacio Guillen's (P) wife, Clementina Guillen-Alejandre, died on July 5, 1996, in an automobile accident at the intersection. Several months before the accident, D had requested §152 funding for this intersection, but the request had been denied. Petitioner renewed its application for funding on April 3, 1996, and the second request was approved on July 26, 1996, only three weeks after the accident occurred. P sought information about accidents at the intersection. P filed an action claiming that D's refusal to disclose the relevant documents violated the State's Public Disclosure Act (PDA). The trial court granted summary judgment in favor of P and ordered petitioner to disclose five documents and pay respondents' attorney's fees. D appealed. P then filed an action claiming that D was negligent for failing to install proper traffic controls at the intersection. Interrogatories seeking information regarding accidents that had occurred at the intersection were served. D refused to comply with the discovery request. P got an order to compel, and D moved for discretionary appellate review of the trial judge's interlocutory order. The Washington Court of Appeals granted the motion and consolidated the appeal in the tort case with the appeal in the PDA action. It held that only one document was protected by §409 because it had been prepared for §152 purposes. The rest were not because D 'carefully requested reports in the hands of the sheriff or other law enforcement agencies, not reports or data `collected or compiled' by the Public Works Department.' D appealed. The Washington Supreme Court's held that §409 was beyond Congress' powers under the Spending, Commerce, and Necessary and Proper Clauses of Article I of the United States Constitution. Barring the admissibility and discovery in state court of accident reports and other traffic and accident materials and `raw data' that were originally prepared for routine state and local purposes, simply because they are `collected' for, among other reasons, federal purposes pursuant to a federal statute' did not reasonably serve any 'valid federal interest in the operation of the federal safety enhancement program.' The Supreme Court granted certiorari.