Washington(CNN) Supreme Court confirmation hearings often develop their own tenor, depending on the nominee and the issues of the day. Even without a choice yet from President Donald Trump, two themes already have emerged: Russia and Roe.

Roe v. Wade, the 1973 decision that made abortion legal nationwide, has been a Senate Judiciary Committee perennial for decades. But the fate of the landmark ruling is likely to consume more of the questioning between senators and the nominee this time simply because Trump, as a candidate, vowed to appoint justices who would reverse Roe and leave abortion law to the states.

Special counsel Robert Mueller's investigation into Russia's interference in the 2016 presidential election and ties to the Trump campaign is already hovering over the Trump Supreme Court selection. Presidential prerogatives would loom even more if the nominee is US Appeals Court Judge Brett Kavanaugh, the short-lister who has had the greatest experience with executive-power dilemmas, as a lawyer with independent counsel Ken Starr's investigation of President Bill Clinton and then as a top aide to President George W. Bush.

Irrespective of the nominee, the televised hearings could preview for the American public controversies that could ultimately reach the justices, including whether a sitting president could be criminally indicted or whether a president may pardon himself.

That latter question was already put to another short-lister, US Appeals Court Judge Amy Coney Barrett, when she was before the Senate Judiciary Committee last September.

On Sunday's edition of CBS News' "Face the Nation," Sen. Richard Blumenthal said, "The President should not be permitted to appoint a justice who will decide whether or not he complies with a subpoena to testify before a grand jury, or pardons himself."

"I believe that whoever is appointed," Blumenthal, a Connecticut Democrat, added, "ought to recuse himself and commit to recusing himself from those kinds of decisions that affect the personal finances or the special prosecutor investigation."

Rarely are commitments made at confirmation hearings and the sessions often become a forum for evasion. Still the back-and-forth between senators and a nominee tends to capture the dominant legal concerns of the day.

In late June 2010, for example, President Barack Obama's appointee Elena Kagan faced senators eager to air their complaints about the Citizens United v. Federal Election Commission ruling issued five months earlier. In fact, Kagan, as the US solicitor general, had argued against that decision lifting federal regulation of corporate and labor campaign spending. Kagan's more serious critics challenged her decision, as dean of Harvard's law school, to temporarily bar military recruiters from campus facilities because of the "don't ask, don't tell" policy against openly gay troops.

In July 2009, skeptics of Obama nominee Sonia Sotomayor, poised to be the first Hispanic justice, focused on racially charged controversies, particularly a 2001 Sotomayor remark that she hoped "a wise Latina woman with the richness of her experiences would more often than not reach a better conclusion than a white male who hasn't lived that life."

More recently, in the March 2017 hearings for Neil Gorsuch, several questions focused on judicial independence -- because of Trump's criticism of judges who had ruled in early litigation against his travel ban tied to majority-Muslim countries.

Notable Kavanaugh and Barrett comments

Trump has said he will make his choice of a successor to retiring Justice Anthony Kennedy pubic next Monday. Among those on his shortlist with Kavanaugh and Barrett are US Appeals Court Judges Thomas Hardiman, who sits on the Philadelphia-based 3rd Circuit, and Raymond Kethledge and Amul Thapar, who both sit on the Cincinnati-based 6th Circuit.

The Starr investigation, for which Kavanaugh worked, was propelled forward partly by a 1997 Supreme Court decision, Clinton v. Jones, that declared that the president could not invoke presidential immunity to postpone a civil lawsuit by Paula Jones, who said he had sexually harassed her when he was governor of Arkansas. The following year, Starr obtained a subpoena to compel Clinton's testimony is a separate matter, involving Monica Lewinsky, a former White House intern with whom Clinton had had a relationship.

But Kavanaugh said after serving with Bush, who named him to the District of Columbia Circuit Court in 2006, he came to believe the demands of the White House too great to subject the president to civil or criminal litigation.

"(T)he indictment and trial of a sitting president," Kavanaugh wrote in a 2009 law review, "would cripple the federal government, rendering it unable to function with credibility in either the international or domestic arenas."

"One might raise at least two important critiques of these ideas," Kavanaugh acknowledged in his essay published in the Minnesota Law Review. "The first is that no one is above the law in our system of government. I strongly agree with that principle. But it is not ultimately a persuasive criticism of these suggestions. The point is not to put the President above the law or to eliminate checks on the President, but simply to defer litigation and investigations until the President is out of office.

"A second possible concern is that the country needs a check against a bad-behaving or law-breaking President. But the Constitution already provides that check. If the President does something dastardly, the impeachment process is available."

Because of the controversy spurred by the Mueller investigation, which Trump has repeatedly deemed a "witch hunt," senators have begun asking lower court nominees about related legal issues, along with the time-tested Roe v. Wade.

Last September, while testifying before the Senate Judiciary Committee for a seat on the Chicago-based 7th Circuit, Barrett said she would follow Supreme Court precedent on Roe, which the high court has said means government cannot impose an "undue burden" on women seeking to end a pregnancy before the fetus is viable.

"Can a president pardon himself?" Sen. Dick Durbin, D-Illinois, asked Barrett in a follow-up written question.

"I have not studied that issue," Barrett responded. "If confirmed and that issue were to come before me as part of a case or controversy, I would resolve that issue as I would any other -- by engaging in the judicial process, which includes examining the facts, reading the briefs, conducting necessary research, listening to the arguments of litigants, discussing the matter with colleagues, and writing and/or reading opinions."

Such may be the guarded tone of many answers, irrespective of the question or of the nominee.