“the U.S. Court of Appeals for the 9th Circuit largely affirmed a lower court ruling that found that the Trump administration was likely guilty of conducting illegal immigration raids in the greater Los Angeles area that violated the Fourth Amendment rights of multiple U.S. citizens.
Generally speaking, Fourth Amendment caselaw requires that an officer must have reasonable suspicion of criminal activity in order to stop someone. In the immigration context, a federal officer must have reasonable suspicion that a person is in violation of immigration law in order to detain them.
In this case, Perdomo v. Noem, the lower court held, and the appellate court agreed, that the Trump administration was apparently carrying out immigration raids and arrests without any semblance of reasonable suspicion, which invariably meant that U.S. citizens were also getting caught up in the federal dragnet.”