An appeals court heard arguments Monday over whether the Trump administration can invoke the Alien Enemies Act to deport migrants it says are Tren de Aragua members.

A federal appeals court appeared skeptical on Monday of lawyers challenging President Donald Trump‘s use of the Alien Enemies Act, as his reliance on the 18th-century law appears increasingly poised to reach the Supreme Court.

The case before one of the most conservative courts in the country is likely to be the first to reach the Supreme Court.