Legal scholars says President Donald Trump’s call for undocumented immigrants to be deported without a court hearing would violate long-standing constitutional rights to due process.

In a tweet posted Sunday, Trump said that undocumented immigrants caught crossing the border should be sent to their country of origin “immediately, with no Judges or Court Cases.”

But legal experts note that the Supreme Court has long held that even non-citizens have the right to due process, the constitutional rule that every person should get a fair hearing in court before facing any punishment.

In fact, the Supreme Court has ruled on the very issue Trump was describing. In a 1953 case, Kwong Hai Chew v. Colding, the Supreme Court found in an 8-1 decision that a permanent resident of the United States could not be deported without a hearing under the constitutional right to due process.

“Although Congress may prescribe conditions for his expulsion and deportation, not even Congress may expel him without allowing him a fair opportunity to be heard,” the court wrote.

During the press briefing Monday, White House spokeswoman Sarah Huckabee Sanders defended the tweet, noting that many undocumented immigrants agree to leave the country without going through the courts.

“Just because you don’t see a judge, doesn’t mean you are not receiving due process,” she said.

The Administration’s critics, however, argued that Trump’s tweet went too far.

“I understand the need to enforce our borders, but there are ways to do that without depriving people of basic rights,” Ron Klain, former chief of staff to Vice President Joe Biden told TIME. “We could increase the number of judges to hear these cases, we could allow people to have ankle bracelets to make them come back and attend their hearings. But if you’re going to start deporting people who have a claim that they’re here lawfully, without a hearing, without a chance to present that claim to a judge, that really puts people’s fundamental rights at risk.”

Trump has also complained about proposals to add more federal immigration judges. A bill from a group of Senate Republicans including Florida Sen. Marco Rubio would add another 225, while a proposal from Republican Sen. Ted Cruz would add 375, but in both cases the total number of judges would still be in the hundreds, not, as Trump has said, in the thousands.

“Hiring many thousands of judges, and going through a long and complicated legal process, is not the way to go — will always be dysfunctional,” Trump wrote in a tweet Monday.

He repeated that exaggerated number in remarks to the press with King Abdullah II of Jordan on Monday afternoon.

“They came in to see me last week; they said, ‘We’d like to hire 5,000 more judges.’ Five thousand,” he said. “You ever hear of thing like that? Judges. Well, we’re appointing 145 judges here, and everyone goes through this extreme vetting process. You’re talking about 5,000. Where do you find 5,000 people to be judges? And you know what it leads? It leads to graft. It leads to a lot of other things.”

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Write to Abby Vesoulis at abby.vesoulis@time.com.