An Associated Press investigation has revealed that, across the United States, police officers abuse their access to confidential databases to look up information on neighbors, love interests, politicians, and others who had no connection to a criminal investigation.

The databases house intensely personal information—not just criminal histories, but car registration, home addresses, phone numbers, and more. According to the Associated Press, officers across the country have used the databases for a wide variety of unauthorized purposes, including stalking ex-girlfriends, looking up personal information for romantic interests, and retaliation against journalists and politicians who provoked the police. Some officers even sold information from the databases.

The extent of the abuse is hard to measure. While the Associated Press investigation turned up hundreds of reports on improper database usage, the amount of reporting varies widely state by state. Some states provide very little information, and others none at all. With police officers making thousands of routine, legitimate queries to databases all the time, it can be difficult to identify abuse of access until an officer acts on the information in a way that generates a complaint. It’s also unclear how often this leads to disciplinary action.

Police have been granted access to a world of private information, and now have very little accountability for how they use it.

This story also raises more concerns about government mass surveillance, like that conducted by the National Security Agency. When the government collects detailed information about its citizens, government employees have access to that information for both legitimate and illegitimate purposes. When the surveillance lacks transparency and accountability, it’s even easier to abuse.

Check out the video below to learn more about surveillance and privacy.