Washington (CNN) -- If confirmed to the Supreme Court as expected, Elena Kagan would work with and independently of Chief Justice John Roberts. That's the nature of the court's internal dynamics, and the concept of the one justice-one vote system in which the chief justice is often called "first among equals."
Roberts' five-year leadership of the nine-member court has frequently been as much a part of Kagan's Senate confirmation hearing this week as the nominee herself. Despite their clear ideological differences, it has been striking how much these two clearly bright legal minds share.
Kagan's candid but cautious approach in three days of hearings looks like it came out of the playbook Roberts used when he went before senators in 2005. She concluded her testimony Wednesday relatively unscathed, clearing the path for a likely confirmation in coming weeks.
In their appearances before the Senate Judiciary Committee, Roberts and Kagan were both conversational and analytical, but neither offered much specificity about how they would rule on hot-button issues. Using a smooth charm offensive, they were very clever in mixing humor and moderation to trump any real substance. They come across as extremely relaxed, smart, and self-confident.
Some lawmakers noted the similarities, not always in a flattering manner.
"We see her gifts and graces in many different ways -- those that are revealed in her humor and her knowledge," said Sen. Jeff Sessions of Alabama, the panel's ranking Republican. "But I think some of the critics who are saying -- who is this nominee, exactly what do you believe -- might find it from the testimony difficult to know, Ms. Kagan, whether you will be more like John Roberts or more like [liberal Justice] Ruth Bader Ginsburg."
Committee Chairman Sen. Patrick Leahy, D-Vermont, noted Kagan's views were not so much out of the mainstream.
"I did not hear her views of the Constitution be to different than those of John Roberts or others," Leahy said.
Part of that similarity in style reflects their backgrounds. Kagan would be the youngest justice, at age 50. Roberts was the same age when he became the 13th chief justice of the United States. They're both Harvard Law graduates, and both clerked in the 1980s for iconic Supreme Court justices -- he for William Rehnquist, she for Thurgood Marshall.
The most important comparison may be their extensive experience as well-connected aides in the White House -- he for Ronald Reagan and George Bush, she for Bill Clinton.
As eager young lawyers, Kagan and Roberts used those government positions to write sharply worded, often blunt memos laying out legal and policy positions on a range of social and political issues such as abortion and affirmative action. A wicked sense of humor was laced throughout many of the documents. They also used their jobs as political springboards, earning the kind of attention that would pay career dividends years later.
Such West Wing policy experience clearly makes them both more comfortable around Washington lawmakers than perhaps other recent court nominees like Sonia Sotomayor and Samuel Alito, who both were decidedly more reserved and low-key in their hearing profile. Kagan and Roberts are wonky but politically and culturally attuned.
One more unusual link: Kagan was nominated in 1999 by Clinton for a seat on the prestigious U.S. Court of Appeals for the District of Columbia Circuit -- often labeled a career stepping stone to the high court, since four current justices came from that bench. But her nomination was never approved by the GOP-controlled Congress, and disheartened, she returned to academia. The court seat was filled a few years later by -- you guessed it -- Roberts.
Kagan has resisted either attacking or comparing herself to the chief justice in her confirmation hearings. For example, she declined to characterize the conservative majority Roberts court as "results-oriented."
Perhaps the defining moment of his 2005 hearings was Roberts' assertion that judges should act like neutral umpires who merely call "balls and strikes." Kagan said she only partly agreed with that analogy.
"It's correct in certain respects, but like all metaphors it does have its limits," she told Sen. Sheldon Whitehouse, D-Rhode Island.
"It's correct insofar as a judge shouldn't root for a certain side in a case," but instead be "neutral" and "fair," she said.
Kagan also noted that Roberts was correct in saying judges need to know they're not "the most important people" in U.S. democracy, and in fact have a "limited role."
But Kagan said the comparison would fail if it suggests rulings on the law are "robotic," adding it gives the false impression that everything "is clear cut" and "there's no judgment in the process." Cases go to the Supreme Court because they are hotly disputed, she noted.
"They're not easy calls," Kagan said, but instead require some "judgment" and "wisdom."
One of the concerns about Roberts was that he had only been a federal judge for little more than two years before being tapped for the high court. Kagan's lack of any judicial experience worries some on both the left and right over what kind of justice she would become. Yet both nominees pledged in nearly the exact same words to put aside their political views when judging.
"I come before this committee with no agenda, no platform," Roberts said. "I will approach every case with an open mind."
"I've learned that we come closest to getting things right when we approach every person and every issue with an open mind," Kagan said.
Sometimes people who share similar personalities often clash. Many legal commentators have noted an often frosty relationship between Kagan and Roberts, when as solicitor general, she argued six cases in the past year before the high court. Justice Antonin Scalia seemed to enjoy Kagan's easy banter, and he joked frequently with her.
But Roberts often took tough stands, questioning Kagan's legal reasoning on several occasions. Part of that was due in no part to conservative skepticism of her defense of the Obama administration's often liberal positions on the law.
The first case she argued before the court was a blockbuster: whether to open up federal campaign spending to corporations -- businesses, unions and advocacy groups -- seeking a greater voice in the crowded political debate, mainly through ads.
Roberts seemed concerned Kagan appeared to abandon at argument a key point made earlier by the administration -- that current campaign spending limits are necessary to ensure corporate speech does not overwhelm the voices of individual voters.
"We do not rely at all on that," Kagan noted in September.
"You are asking us to uphold [past precedent on spending limits] on the basis of two arguments, two principles, two compelling interests we have never accepted in the expenditure context," he said.
"Fair enough," Kagan brusquely acknowledged. She lost the case, when the court in January loosened those spending restrictions.
In March, Roberts labeled as "absolutely startling" the solicitor general's argument that when one federal prosecutor drops criminal charges, another prosecutor need not do the same.
"The different U.S. attorneys all work for your boss, right?" Roberts said. "They work for the attorney general," and his final decision holds.
Not willing to back down, Kagan argued various individual offices should be allowed discretion to decide such matters as they fit. "The United States government is a complicated place," she said.
"I take your word for it," Roberts said with a smile, drawing laughter in the courtroom.
For two strong-willed ambitious personalities, the chief justice -- in that instance at least -- got the last word.