Wednesday’s order by the mayor to police to stop pulling over motorists for low-level offenses critics claim leads to disproportionate stops of minorities drivers. Philadelphia is the largest U.S. city to ban pretextual stops.

Mayor Jim Kenney’s executive order puts into effect a bill that was passed by the City Council last month, the Driving Equality Bill. Officers cannot pull over vehicles for “secondary violations” such as improperly displayed inspection stickers or registration stickers.

Law enforcement advocates claim that such stops can uncover illegal drugs or weapons. The U.S. Supreme Court ruled that they were allowed in 1996. Critics say that the practice has resulted in Black and Latino motorists being stopped and searched at excessive rates, and sometimes being held for minor infractions.

This has led to some high-profile deaths. Sandra Bland, Walter Scott and Duante Wright were all pulled over initially for pretextual stops.

Minnesota has at least two prosecutor’s departments that have stated they will not prosecute motorists who are charged with crimes related to pretextual stops.

Philadelphia, which is the sixth-largest city in the United States, has issued similar bans to smaller municipalities. Virginia, on the other hand, banned stops for minor offenses such as smelling marijuana, excessively tinted windows, or hanging objects from the rearview mirror.

The Defender Association of Philadelphia examined 300,000 traffic stops from the previous year and concluded that the new law would stop a large number of them in the future. A second bill was also passed by Philadelphia’s City Council, which requires that Philadelphia collect and publish data about traffic stops. This includes the reason for the stop and demographics of the driver, passengers, as well as the location of the stops.

The city settled a discrimination case against Philadelphia police officers in 2011. They were accused of targeting Black residents for pedestrian searches. Reform advocates argue that officers used pretextual traffic stops to search Black drivers, despite the fact that pedestrian stops were closely monitored.