If your travels don't take you through large transportation hubs like Washington DC's Union Station and the Port Authority Bus Terminal in New York, you may be surprised to hear that the Transportation Security Administration (TSA) isn't just in airports anymore. The agency has "VIPR" teams (Visible Intermodal Prevention and Response) performing random security sweeps at train stations, sporting and music events, highway weigh stations, Republican and Democratic National Conventions, and more, according to a new report from The New York Times. The program first started in 2005 in response to the Madrid train bombings a year earlier, and it hasn't been run in secret (though the reach of VIPR has expanded over the years, with a most recent budget of $100 million for several hundred employees).

An audit from the Department of Homeland Security questions the utility of the program, pointing out that it's questionable whether checkpoints are set up in response to credible threats and that the air marshals who often make up the teams aren't trained for mass transit screenings. Civil liberties groups and others, meanwhile, call the searches, which are carried out without probable cause, a violation of Fourth Amendment rights against unreasonable searches and seizures. For its part, the TSA points to Supreme Court decisions which support these "special needs" and "administrative searches" as an exception to the Bill of Rights, but it's unclear how those rulings apply outside of airports. For more, be sure to read the full New York Times report.