Earlier this month, federal immigration agents raided dozens of 7-Eleven Inc. stores nationwide and arrested 21 people. While the early-morning raid was the biggest crackdown under the Trump administration on a company suspected of hiring undocumented workers, it certainly will not be the last, legal experts said.

New U.S. Attorney General Jeff Sessions has not been shy about one of his agency’s new priorities—illegal immigration—and has ushered in an era in which previously unenforced conduct related to the employment of unauthorized workers is now fair game.