The idea behind the national license-plate recognition database, which would have drawn data from readers that scan the tags of every vehicle crossing their paths, was to help catch fugitive illegal immigrants, according to a DHS solicitation. But the plan raised concerns that the movements of ordinary citizens who are under no criminal suspicion could be scrutinized.

“The solicitation, which was posted without the awareness of ICE leadership, has been cancelled,” ICE spokeswoman Gillian Christensen said in a statement. “While we continue to support a range of technologies to help meet our law enforcement mission, this solicitation will be reviewed to ensure the path forward appropriately meets our operational needs.”