WASHINGTON (NEXSTAR) — The United States Supreme Court began hearing arguments Tuesday in a case that is asking justices to strike down an old immigration law that’s rarely been enforced.

The argument is that the law violates the first amendment. The 9th U.S. Circuit Court of Appeals ruled the law is unconstitutional but the Trump administration wants the high court to uphold it.

The little-known law makes it a federal crime to “encourage” someone to come to or remain in the United States illegally. Violating the law is punishable by up to five years in prison.

Attorney Mark Fleming represents an immigration lawyer who was charged under the law. He says it is a first amendment violation and overly broad.

“This isn’t about smuggling or trafficking. It’s about just encouraging,” he said. “It would capture a teacher who says to an undocumented student, ‘you should stay here and be educated in the United States.’ It would cover a doctor who says to a patient, ‘you should stay here so I can treat your cancer.'”

The immigration lawyer at the center of the case was also charged with running an immigration fraud, taking money from immigrants while knowing she could do nothing to help them.

The Department of Homeland Security said it would not comment on the case because it’s pending before the U.S. Supreme Court. But in court, the government’s lawyer argued the immigration statute has never been used only to prosecute free speech.

Chief Justice John Roberts on Tuesday asked the government’s lawyer whether family members could be prosecuted for wishing they weren’t separated. Brian Griffey with Amnesty International says yes.

“A grandchild who’s wishing her grandmother could stay in the U.S. even though she doesn’t have any documentation could be considered by the Trump administration to be a human smuggler,” Griffey said.

“It can’t have a statute that’s overbroad sitting on the books, terrifying people that want to engage in free speech,” Fleming added.

A decision in the case is expected by June.

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