WASHINGTON (AFP) - It is pretty much unheard of for a US Supreme Court justice to speak openly about politics. But its aging doyenne Ruth Bader Ginsburg sure did, blasting Donald Trump as a phony.
Now, Trump is questioning Ginsburg's mental acuity and calling on her to resign.
The editorial boards of the Washington Post and The New York Times say the liberal justice should have kept quiet. And even some of her ideological allies say she goofed.
Ginsburg, 83, dropped all pretense of maintaining a judge's customary reserve in two recent interviews in which she talked about Trump.
"He is a faker," Ginsburg said Monday of presumptive Republican presidential nominee Trump in an interview with CNN.
"He has no consistency about him. He says whatever comes into his head at the moment," said the Brooklyn-born justice, a petite but tough-as-nails figure who has earned the nickname "Notorious RBG" - a play on the stage name of the late rapper Notorious BIG.
"He really has an ego," she said of Trump.
Trump hit back at the leader of the court's progressive wing, first saying her comments were "highly inappropriate" and then suggesting she is getting senile.
"Justice Ginsburg of the US Supreme Court has embarrassed all by making very dumb political statements about me. Her mind is shot - resign!" Trump wrote on Twitter in the early hours of Wednesday.
Ginsburg told The New York Times in an interview published Sunday that the stakes in the 2016 election were positively huge.
"I can't imagine what this place would be - I can't imagine what the country would be - with Donald Trump as our president," she said.
"For the country, it could be four years. For the court, it could be - I don't even want to contemplate that," said the judge.
In the CNN interview, she also questioned the fact that Trump has avoided releasing his income tax returns, which is standard practice among White House hopefuls.
Ginsburg was appointed to the court in 1993 by then president Bill Clinton, a Democrat. The woman has sartorial style evoking another era, wearing gloves and a lacy collar that sometimes overlays the neckline of her black judge's robe.
And she has clout. Last year, she was named to Time's list of the 100 Most Influential People in the world.
As a lawyer, Ginsburg was a pillar of the fight for women's rights in the 1960s and '70s. She has survived cancer several times. She is wildly popular among American liberals, particularly young ones.
Ginsburg recently demonstrated her position firmly within the court's progressive wing by voting to strike down a Texas law that put restrictions on abortion clinics. Her position prevailed, by a vote of 5-3.
Ginsburg's opinions are often at odds with those stated by Trump and other conservatives.
But a legal opinion is one thing, and open criticism of a candidate for public office is quite another.
The Supreme Court normally has nine justices but has been one short since the conservative Antonin Scalia died in February.
The court is now evenly split between conservatives and liberals, who include Ginsburg.
Worried that a court until now dominated by conservatives could now tip in the liberals' favor, President Barack Obama's Republican foes in the Senate have refused to vote on or even hold a hearing on his nominee to replace Scalia, Merrick Garland.
They insist the decision must wait until after voters choose Obama's successor in November.
Ginsburg's comments - which stand out even more because her seven colleagues on the bench have not weighed in on the election - are seen by many as reflecting her independent spirit.
US judges are generally bound by a code of conduct which, among other things, bars them from publicly opposing or endorsing a candidate for office. There is however no legal requirement for Supreme Court justices to stay silent.
Criticism for Ginsburg's remarks is coming from people other than those in the Trump camp.
"I find it very peculiar, and I think it's out of place," the Republican speaker of the House of Representatives, Paul Ryan, told CNN.
"For someone on the Supreme Court who is going to be calling balls and strikes in the future based upon whatever the next president and Congress does, that strikes me as inherently biased and out of the realm," Ryan said Tuesday.
When asked about the escalating face-off, White House spokesman Josh Earnest declined to comment on the substance, but said, in a knock on Trump's accusations: "I would not call her competence into question."
On a lighter note, he joked: "She didn't earn the nickname the Notorious RBG for nothing."
The Washington Post, which rarely goes easy on Trump, said in an editorial that while it may agree with what Ginsburg said about him, her candor was "inconsistent with her function in our democratic system."
The New York Times offered a similar editorial, saying, "Washington is more than partisan enough without the spectacle of a Supreme Court justice flinging herself into the mosh pit."