Supreme Court Chief Justice John Roberts confirmed the authenticity of a draft opinion that would throw out longstanding abortion rights.
An investigation was ordered by Roberts.
The chief justice said that the betrayal of the confidences of the Court would not succeed.
The marshal of the court has been directed to investigate the source of the leak.
The high court does not publish draft opinions in advance, which is unusual.
Roberts noted that the court shares drafts of opinions internally long before they are issued publicly.
According to the opinion obtained by Politico, the draft was created in February.
The justices, law clerks and other employees of the court are dedicated to the rule of law, according to Roberts.
Court employees have a tradition of respecting the confidentiality of the judicial process. He said that this was a singular and egregious violation of the trust that the court and the community of public servants have in each other.
The publication of the draft opinion went off like a bomb in Washington, triggering waves of shock and fury from Democrats who are now pushing for Congress to codify abortion rights through legislation.
Republicans decried the leak and many called for an investigation. The GOP lawmakers who commented on the draft opinion praised the ruling for putting the decision about abortion in the hands of the states.
The opinion was written by Justice Samuel Alito, one of six conservatives on the court that has moved to the right in the wake of the Trump administration.
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