An order signed by Federal Circuit Chief Judge Kimberly Moore said a three-judge committee had determined that Judge Pauline Newman, who is 95, may "suffer a disability that interferes with her ability to perform the responsibilities of her office."
Newman is also under investigation for misconduct for refusing to cooperate with the probe or submit to a medical evaluation, Moore said in the order, dated Thursday.
Newman and Moore did not immediately respond to emailed requests for comment.
In an earlier order in March, Moore said Newman had shown signs of cognitive and physical impairment, delayed filing opinions, disclosed sensitive medical information to her staff and allowed one of her law clerks to exhibit unspecified "unprofessional and inappropriate behavior."
The March order said that half of the court's active judges expressed concern about Newman's mental fitness. Newman had refused to consider senior status, a form of semi-retirement, calling herself the only person on the court "who cared about the patent system and innovation policy," the order said.
Newman is a leading intellectual property law jurist and a prominent dissenter on the patent-focused Federal Circuit, which often hears major cases involving technology and pharmaceutical companies. She was appointed to the bench by Republican President Ronald Reagan in 1984.
The March order said Newman has participated in 60 cases since June of last year, while the average active judge participated in 116.
The Federal Circuit acknowledged the probe in a Friday statement. It said court officials "all recognize and admire the lifelong contributions of the justly esteemed Judge Newman," and "are committed to fulfilling their difficult obligations in this process."
It is highly unusual for a U.S. judge to face a complaint from a colleague on the bench, especially on an issue as delicate as their competence to serve.
Arthur Hellman, a University of Pittsburgh law professor who studies the federal courts, said judges typically handle concerns about a colleague’s age or fitness through closed-door conversations, sometimes involving the judge’s family.
“In the overwhelming majority of cases, it's dealt with without any sort of formal proceeding and without any sort of public knowledge,” Hellman said.
Federal judges serve lifetime appointments in the United States. A 1980 law allows for complaints against them for misconduct or if a disability calls into question their ability to serve.
The average age of federal appeals court judges was about 65 in 2017, according to a report from the Congressional Research Service.
Some lawyers who practice before the Federal Circuit said they found the Newman probe surprising.
“There’s no clear indication when you’re around Judge Newman that she’s not understanding things,” said Blair Jacobs, a patent law attorney at law firm McKool Smith who said he was last before the judge in February.
The committee investigating Newman will report its findings to the Federal Circuit’s judicial council, which could reject the complaint or impose sanctions, including a private censure or recommendation that the judge retire.
If a judge refuses to retire take senior status, the council can certify that they have a disability, allowing the U.S. president to nominate another judge.