At issue is a complicated question: Should sheriffs keep undocumented immigrants in their jails for more time than otherwise necessary so that Immigration and Customs Enforcement (ICE) officers can pick them up to be deported?

The White House is demanding sheriffs do just that, by honoring ICE’s requests that sheriffs keep certain people locked up long enough for the agency to take them into custody. Those requests are called detainers. And many sheriffs would happily comply – except that federal courts have ruled repeatedly that the Fourth Amendment bars them from keeping an undocumented immigrant in jail who would otherwise go free.

“If we violate the law by doing what they ask us to do, we’re subjecting ourselves, no question, to civil liability and civil rights violations,” Gualtieri said.