The decision lets the Trump administration halt, for now, a program that lets migrants from Cuba, Haiti, Nicaragua and Venezuela live and work in the U.S. for up to two years.

The administration had asked the court to allow it to end deportation protections for more than 500,000 people facing dire humanitarian crises in their home countries.

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.