As Supreme Court justices circulate draft opinions among themselves and respond to each other’s writing, no two justices engage in a tit-for-tat like Antonin Scalia and John Paul Stevens.

These defenders of conservatism and liberalism, respectively, disagree on big issues, of course, but they are also the two most likely to tussle down in the weeds — on the meaning of a statute, interpretation of precedent or nuances of a legal test. It is not unusual for Scalia to make some assertion that sets off Stevens, who then fires back in his opinion, which prompts Scalia to return the volley, which gets Stevens going again.

That happened in this week’s case of Shady Grove Orthopedic Associates v. Allstate Insurance, a complicated dispute that led to a 5-4 decision letting certain class-action lawsuits barred from state court be heard in federal court. Scalia wrote for a plurality and needed Stevens’s fifth vote for the judgment. Stevens penned a separate concurring opinion. The two feuded over legal reasoning, and by the time Scalia was done answering Stevens’s escalating arguments he had crafted a whole separate section of his opinion that opened with the sentence: “A few words in response to the concurrence.” Several hundred words followed.

As they poked holes in each other’s rationale, Scalia charged Stevens with being “unfaithful” to statute and “greatly exaggerat[ing]” how Scalia had spurned a precedent. Stevens labeled Scalia’s legal test “empty” and said his interpretation of the disputed law was “not much more determinative than mine.” The case had been argued on Nov. 2, and some of this back-and-forth likely led to its being unresolved for nearly four months.

Their dueling rhetoric contributed to the delay in Citizens United v. Federal Election Commission, which came out January 21, after the case had been argued in September and put on a fast-track of sorts. As I noted in an earlier post (Jan. 24), Stevens devoted much of his dissenting opinion in that case to Scalia’s concurrence. (Justice Anthony Kennedy had written the majority opinion.)

Stevens, 89, and Scalia, 74, are two of the more intellectual members of the bench, and they like and respect each other. Scalia revels in this verbal jousting. Stevens finds it more wearying. “He’s got to have the last word,” he once told me of Scalia. “But is it really worth it?”

I think they’ll both miss it when Stevens is gone.

Supreme Court Justice Samuel Alito considered his Senate Judiciary Committee hearings so painful that for months after his 2006 confirmation he would try to avoid the Hart building where the nomination hearings were held. “I cross to the other side of the street,” he said. “I quicken my step until I’m well past the building.”

It’s likely Justice Alito now feels that way about the Capitol, where his disagreement with President Obama on Citizens United v. FEC during the State of the Union was seen by a national television audience.

I was traveling when most of the criticism (some directed at Alito, some at Obama) played out in news reports and cable chatter, and I won’t echo that. I will only add what I know of Alito from my interviews with him. He has a quiet demeanor yet a definite contrary streak.

While the TV audience saw Alito mouth what appeared to be “not true,” Justice Sonia Sotomayor next to him apparently heard nothing. On the video, she doesn’t respond in any way. He may be a constant grimacer (he didn’t look happy at last year’s Obama Inauguration either), but Alito is simply not a talkative sort. He likes to work at home alone, especially when he is writing opinions. On the bench during arguments, other justices sometimes turn to a colleague to whisper a comment or wisecrack. Not Alito. He is in his own space. Some White House aides who accompanied him on courtesy calls to senators before his hearings said they had trouble making small talk with him.

I’ve found Alito relatively easy to talk to – yet also ready to voice the kind of contrary view the nation saw Wednesday night. When I interviewed him for my Scalia biography, Alito said he admired Scalia but found his originalist approach at times lacking. “To say that you’re an originalist doesn’t really decide the case. Originalism gives you a principle to apply. Very often, particularly in areas where things have changed so much, identifying the principle doesn’t really decide the case.” An example of where their originalism diverges: Alito and Scalia disagree on the Sixth Amendment, specifically on what it dictates about judges’ power in criminal sentencing and on the reach of defendants’ right to be confronted by the witnesses against them.

Alito, who like Scalia is a consistent conservative, took offense at media commentators of years back who dubbed the then-appeals court judge “Sc’Alito.”

“I was insulted by it,” Alito told me, “in the sense that I knew the only reason it was done was because of the fact that we were both Italians. I was flattered if people thought I wrote like him or thought like him. But just sort of lumping the two Italians together, I thought, was not appropriate.”

On the personal side, Alito made clear he is no Scalia, who is known for living large (duck hunting with Dick Cheney, the opera with Ruth Bader Ginsburg) and is definitely not a stay-at-home-alone guy. Justice Alito said he didn’t like to play poker or bridge and tended not to socialize much. “I am a very boring person,” he quipped. Well, as of now, three days after the State of the Union speech, the recorded “views” on YouTube of Alito’s response to Obama are in the hundreds of thousands.

As legal commentators continue to debate last Thursday’s decision in Citizens United v. Federal Election Commission, I want to add a few observations related to Justices Scalia and Stevens. As Stevens read his poignant — sometimes halting — dissenting statement from the bench, he noted that the “seed that flowered” in the majority opinion had been planted by dissenters in the 1990 Austin v. Michigan Chamber of Commerce. In his written opinion Thursday, Stevens took specific aim at Scalia– an architect of the view that prevailed last week.

The majority decision was penned by Justice Kennedy, of course, yet Citizens United is another example of the success Scalia has enjoyed in recent years on the new Roberts Court. At one point, Justice Stevens wrote, “All of the majority’s theoretical arguments turn on a proposition with undeniable surface appeal but little grounding in evidence or experience, ‘that there is no such thing as too much speech.’” That quote is from Scalia’s dissenting opinion in Austin. Stevens went on to say, “In the real world, we have seen, corporate domination of the airwaves prior to an election may decrease the average listener’s exposure to relevant viewpoints, and it may diminish citizens’ willingness and capacity to participate in the democratic process.” Stevens then said in a footnote of the notion of “no such thing as too much speech”: “Of course, no presiding person in a courtroom, legislature, classroom, polling place, or family dinner would take this hyperbole literally.”

I’m not sure Scalia wouldn’t.

I was also reminded as the Court majority gave short shrift to Congress of something Justice Scalia had said during oral arguments in the case last September and of his overall view of the legislative branch. “Congress has a self-interest,” he told U.S. Solicitor General Elena Kagan. “We are suspicious of congressional action in the First Amendment area precisely because we – at least I – I doubt that one can expect a body of incumbents to draw election restrictions that do not favor incumbents. Now is that excessively cynical of me? I don’t think so.”

Well, maybe. Scalia cut his teeth in Washington in the Nixon and Ford administrations and, in the post-Watergate era, developed an antagonism toward Congress. He was constantly going up to the Hill to testify on behalf of executive privilege and against disclosure of White House documents. He sparred repeatedly with Sen. Edmund Muskie of Maine, U.S. Rep. Otis Pike of New York, and U.S. Rep. Father Robert Drinan of Massachusetts – all Democrats trying to pry information from the executive. I found in my research for American Original that Scalia’s experiences in the 1970s led him to enduringly value executive power and to consider Congress an adversary.

Finally, I’ve been asked for my take on some of the difficulty Justice Stevens’s had when he spoke from the bench last week. As he read excerpts of his dissent, going on for twenty minutes, he stumbled on some words. Tony Mauro wrote in the Legal Times blog that it was “painful” to hear Stevens speak, and Jan Crawford of CBS said she thought she was witnessing a “different” person. For my part, I thought Stevens’s mix of passion and weariness revealed his sense of the changed Court. As he began his remarks he observed that when he and Justice Sandra Day O’Connor jointly wrote a campaign-finance decision in 2003 (McConnell v. Federal Election Commission, rejecting a broad challenge to the McCain-Feingold law and the provision in dispute last week), they had begun with the belief that Congress could restrict corporate spending in elections. As Stevens spoke despairingly, he condemned the reversal of that notion. “The only relevant thing that has changed since Austin and McConnell is the composition of this Court,” he said in his opinion.

I know from my interviews with Justice Stevens that he considered retiring in the late 1980s, after he hit age 65. He stayed on the bench partly because of the role he thought he could play as the Court moved to the right with appointees of Ronald Reagan and the first President Bush. Stevens will be 90 in April. This time around, his options for the long-term are different.

The week is about to end without a ruling from the Supreme Court in Citizens United v. Federal Election Commission, regarding governments’ authority to regulate corporate and labor union spending in elections. Both sides have been anxiously awaiting a decision in the case that was argued last September and could affect big-money expenditures in this fall’s mid-term elections and all future races.

So sure were many campaign experts that the ruling was coming this week that they deluged reporters with notices of planned teleconferences and statements of how significant the decision was likely to be.

I cannot blame anyone for trying to predict the Court, especially when so much is at stake. But having gone through hundreds of once-private documents in judicial archives and seen how eleventh-hour switched-votes play out, I know how many factors can delay a case. A justice whose vote is crucial to the majority could be wavering. There could be an escalation in rhetoric between the majority and dissenting opinions. And those are just the predictable hold-ups.

I can recall numerous cases from my research on Antonin Scalia and Sandra Day O’Connor of flipped votes detected only after a justice’s private papers became public.

In the 1988 case of Bowen v. Massachusetts, between the federal government and states over Medicaid expenditures, Justice Scalia started with the opinion for the court but lost it when Justice William Brennan reconsidered competing legal rationales. One of the lawyers in the case told me recently that he wouldn’t have known that the outcome had changed if he hadn’t read about the behind-the-scenes maneuverings. Sometimes, there’s enough of a ‘we were robbed’ tone to the dissenting opinion to suspect that a justice changed his or her vote. But often the public opinions give no clue.

In the 1994 Holder v. Hall dispute over the scope of the landmark Voting Rights Act, Scalia started with the majority and the opinion for the Court, but then justices on his side began splintering off. Chief Justice William Rehnquist reassigned the opinion to Anthony Kennedy. That case, by the way, was argued on Oct. 3, 1993 and not decided until June 30, 1994. Could we be waiting for Citizens United until June?

I solved a mystery in the 1989 case of Wyoming v. United States, involving water rights for Native Americans on the Wind River Reservation, while I was doing research on O’Connor. The United States government, as a trustee for the tribes, had successfully contested a Wyoming state policy that voided the water rights. In its appeal to the Court, Wyoming claimed the rights had lapsed when the Indians failed to invoke them for irrigation or other projects. O’Connor was writing an opinion for a five-justice majority that sided with Wyoming and would deny the tribe water rights. As Justice Brennan began a draft of his dissent in the case, he referred to the Bible, “The Court might well have taken as its motto for this case the words of Matthew 25:29: ‘but from him that has not shall be taken even that which he has.’”

 But then suddenly everything changed. In late June, O’Connor sent a note to her fellow justices saying she had discovered her family’s Arizona ranch was named in a similar water-rights lawsuit, and she wanted to disqualify herself from the Wyoming matter. Without O’Connor’s vote, the Court was split 4-4 and the tie vote automatically affirmed the lower-court decision favoring the U.S. government as trustee for the tribes. The Court announced its resolution in one sentence. In private, O’Connor had closed her recusal note, which I first found in the papers of the late Justice Thurgood Marshall, with, “The unexpected has become the order of the day this term.” Maybe we’re in for another one of those terms.

When Citizens United finally is handed down, we’ll get some indication of what was happening. And then, years from now, if one of the justices makes his or her papers available – and if any of us are still around to read them – we’ll know much more. Those are big Ifs.

When I asked Justice O’Connor recently about when her archives might be available and if I might find some gems there, she said, “Don’t hold your breath.”