Irin Carmon is co-author of "Notorious RBG: The Life and Times of Ruth Bader Ginsburg" and a national reporter at MSNBC.

Despite their differing judicial philosophies, Antonin Scalia and Ruth Bader Ginsburg shared a strong bond. (Photo by Alex Wong/Getty Images)

The question comes every time. “Excuse me, but there’s something I don’t understand about Justice Ruth Bader Ginsburg,” someone will ask my co-author and me at each event since we published “Notorious RBG,” a lighthearted biography of the justice. “How could she possibly be friends with Scalia?”

Now that Senate Republicans have vowed, mere hours after the death of Justice Antonin Scalia, to block any Obama nominee to replace him, it’s worth considering the answer.

Nino and RBG, the court’s most famous odd couple friendship, the subject of the recent comic opera “Scalia/Ginsburg,” stood as an example of warmth and professionalism across traditional divides. For Ginsburg, who has been outnumbered throughout her career, it was also about making the institution work, no matter their disagreements.

Sure, the two justices, friends since the 1980s, had some things in common. They shared a love of opera. They came from outer-borough New York City. Before they were two of the nine, they were contemporaries as law professors and served together on the United States Court of Appeals for the D.C. Circuit. But the reserved Clinton appointee and the bombastic Reagan pick had vastly different views on the constitution and the role of the court.

While speaking with Washington Post reporter Abby Phillip, Former president Bill Clinton offers condolences to the Scalia family Saturday, Feb. 13. (Abby Phillip)

Had Scalia been a justice when Ginsburg was arguing women’s rights cases before the court throughout the 1970s, he certainly would have have voted against her. He wrote the solo dissent to her majority in U.S. v. Virginia, the opinion that ended women’s exclusion from the Virginia Military Institute, and formed the capstone of her lifelong fight for gender equality. “This is not the interpretation of a Constitution,” Scalia complained, “but the creation of one.” Scalia bitterly opposed the Supreme Court’s gradual recognition of rights for gays and lesbians; Ginsburg was the first justice to preside over a same-sex marriage. Scalia referred to the Voting Rights Act, the law protecting ballot access for the historically disenfranchised, as one of several “racial entitlements” that Congress would be hard-pressed to end; Ginsburg ferociously dissented when the court gutted it.

And yet. One former clerk told us Scalia was Ginsburg’s favored souvenir shopping buddy when they traveled together. On a trip to India, they famously rode an elephant, with Scalia sitting up front. What about feminism? “It had to do with the distribution of weight,” Ginsburg deadpanned slyly. They shared New Year’s Eves with their families and friends: “Scalia kills it and Marty [Ginsburg, Ruth’s husband] cooks it,” recalled one guest, former Bush solicitor general Theodore Olson. “I never heard them talk about anything political or ideological, because there would be no point,” Ginsburg’s grandson, Paul Spera, told us. In 2010, when Chief Justice Roberts announced Marty’s death from the bench, Scalia wiped tears from his eyes.

“If you can’t disagree ardently with your colleagues about some issues of law and yet personally still be friends, get another job, for Pete’s sake,” is how Scalia once described their lifetime appointments. “As annoyed as you might be about his zinging dissent, he’s so utterly charming, so amusing, so sometimes outrageous, you can’t help but say, ‘I’m glad that he’s my friend or he’s my colleague,’ ” Ginsburg said. Sometimes, she said, she had to pinch herself to not laugh in the courtroom when Scalia said something audacious.

Even in that VMI case, Ginsburg was grateful for how Scalia disagreed: giving her a copy of his dissent as soon as possible, so she could properly respond. “He absolutely ruined my weekend, but my opinion is ever so much better because of his stinging dissent,” she said. Whether or not it was how Scalia saw it, for Ginsburg their public friendship also made a statement about the court as an institution: that it was strengthened by respectful debate, that it could work no matter how polarized its members were.

Ironically, Scalia’s death has laid bare just how endangered such comity now is in Washington. And Ginsburg, for one, has acknowledged it. When I interviewed the justice last year, I asked her about the court chipping away at the major civil rights legislation of the last century. She responded by talking about another branch of government, Congress. Specifically: its inability to act as it did after the court’s decision in Ledbetter v. Goodyear, when legislators took up her dissent’s call to fix what Ginsburg saw as a grievous injustice to women denied fair pay.

“At the moment, our Congress is not functioning very well,” she told me, and laughed. She added, “The current Congress is not equipped really to do anything. So the kind of result that we got in the Ledbetter case is not easily achieved today. Someday, we will go back to having the kind of legislature that we should, where members, whatever party they belong to, want to make the thing work and cooperate with each other to see that that will happen. I mean, it was that way in 1992 when I was nominated for this good job. There were only three negative votes. And my hope and expectation is that we will get back to that kind of bipartisan spirit.”

Friendship across ideological lines may not technically be a thing of the past. After all, Ginsburg’s younger colleague Justice Elena Kagan gamely took up arms to hunt with Scalia after Republican senators challenged her on guns during her confirmation process. But judging from the political deadlock that has already emerged around Scalia’s replacement, threatening the very functioning of the court, that bipartisan spirit is long gone.

Irin Carmon is co-author of “Notorious RBG: The Life and Times of Ruth Bader Ginsburg” and a national reporter at MSNBC. 

Washington Post reporter Robert Barnes explains where the Supreme Court stands after the death of Justice Antonin Scalia and how the vacant seat will impact the presidential election. (Whitney Leaming/The Washington Post)