WASHINGTON (AP) — President Donald Trump has stated that he is seriously considering the possibility of “revoking” the U.S. citizenship of actress and comedian Rosie O’Donnell, a long-term adversary, despite a longstanding Supreme Court decision that forbids the government from taking such an action.

“Due to the fact that Rosie O’Donnell is not beneficial for our Great Country, I am giving serious thought to revoking her Citizenship,” Trump wrote in a social media post on Saturday. He also mentioned that O’Donnell, who relocated to Ireland in January, should remain there “if they accept her.”

Their public criticisms of one another have continued for many years, often in a bitter exchange that started well before Trump entered the political scene. Recently, O’Donnell has used social media to condemn Trump and his administration’s recent decisions, including the passing of a large GOP-favored tax breaks and spending cuts plan.

It’s just the latest threat by Trump to revoke the citizenship of people with whom he has publicly disagreed, most recently his former adviser and one-time ally, Elon Musk.

But O’Donnell’s situation is notably different from Musk, who was born in South Africa. O’Donnell was born in the United States and has a constitutional right to U.S. citizenship. The U.S. State Department notes on its website that U.S. citizens by birth or naturalization may relinquish U.S. nationality by taking certain steps – but only if the act is performed voluntary and with the intention of relinquishing U.S. citizenship.

Amanda Frost, a law professor at the University of Virginia School of Law, noted the Supreme Court ruled in a 1967 case that the Fourteen Amendment of the Constitution prevents the government from taking away citizenship.

“The president has no authority to take away the citizenship of a native-born U.S. citizen,” Frost said in an email Saturday. “In short, we are nation founded on the principle that the people choose the government; the government cannot choose the people.”

O’Donnell moved to Ireland after Trump defeated Vice President Kamala Harris to win his second term. She has said she’s in the process of obtaining Irish citizenship based on family lineage.

Responding to Trump Saturday, O’Donnell wrote on social media that she had upset the president and “add me to the list of people who oppose him at every turn.”