It’s more about the filing of the complaint than actually succeeding on it,” said Aaron Katz, an adjunct law professor at Boston University School of Law.

The U.S. Department of Justice filed suit against the city of Boston over its "sanctuary city laws." Mayor Michelle Wu said the city "will not yield."

The lawsuit filed in Boston federal court marked the latest in a legal campaign the Republican president's administration has waged over laws adopted by so-called "sanctuary jurisdictions" run by Democrats. The administration contends these laws are impeding Trump's mass deportation agenda.