The Tennessee Highway Patrol provides assistance to motorists who need help. It investigates traffic accidents involving property damage, personal injury, or death. The agency works with prosecutors in the prosecution of cases in which the use of drugs or alcohol contributed to accidents causing personal injury or fatalities. In addition to traffic law enforcement, the Tennessee Highway Patrol has responsibility in criminal interdiction, which involves the suppression of narcotics on the state's roads and highways, including Interstate Highways. It is the agency responsible for conducting background checks on applicants for permits to carry handguns.