An appeal that landed at the Supreme Court Tuesday could test the justices’ emerging concern about President Donald Trump’s aggressive deportation policies and whether he is willing to defy judicial orders.

The US sued four “sanctuary cities” in New Jersey, claiming they are blocking the work of federal immigration officials, as the Trump administration seeks to remove obstacles to its mass deportation plans.

Farm owners and workers alike have been on edge in the month since US Border Patrol officers detained eight Mexican men on Vermont’s largest dairy operation, Pleasant Valley Farms.