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Senator Lindsey Graham, Republican of South Carolina and the chairman of the Judiciary Committee, opened Wednesday’s hearing by proclaiming Judge Amy Coney Barrett’s coming confirmation a historic victory for conservative women who he said have faced steeper obstacles in public life than liberal women.
“This is the first time in American history that we’ve nominated a woman who is unashamedly pro-life and embraces her faith without apology, and she is going to the court,” Mr. Graham said.
Judge Barrett, President Trump’s Supreme Court nominee, has declined repeatedly during the hearings to answer how she would rule on a challenge to the Roe v. Wade decision that established abortion rights, but has made clear that she opposes abortion rights.
“This hearing, to me, is an opportunity to not punch through a glass ceiling, but a reinforced concrete barrier around conservative women,” Mr. Graham said as the second day of questioning by senators began. “You’re going to shatter that barrier.”
Mr. Graham, who is in a tough re-election campaign, echoed statements on Tuesday from the panel’s two Republican women, both of whom argued that conservative women had been marginalized for their beliefs.
“I have never been more proud of the nominee than I am of you,” he said. “This is history being made, folks.”
Later, Senator Josh Hawley, Republican of Missouri, echoed Mr. Graham’s praise as he concluded his questions, announcing that he would vote for Judge Barrett and saying: “There’s nothing wrong with confirming to the Supreme Court of the United States a devout, Catholic, pro-life Christian.”
President Trump’s attacks on the rule of law and the judiciary hung over the proceedings, as Judge Barrett repeatedly parried questions from Democrats about how she viewed matters of presidential power, including whether a president could defy a Supreme Court ruling or pardon himself.
Asked by Senator Patrick J. Leahy of Vermont whether courts had the power to enforce their rulings if a president disobeyed, the judge would not give a definite answer.
While Judge Barrett said that “no man is above the law,” she added, “as a matter of law, the Supreme Court may have the final word, but it lacks control about what happens after that.”
Mr. Leahy tried again, asking whether a president who refused to follow a court ruling would pose a threat to the constitutional system of checks and balances.
She would not directly answer.
“As I said, the Supreme Court cannot control whether or not the president obeys,” she said, noting that Abraham Lincoln had once disobeyed a lower court order during the Civil War.
Judge Barrett was similarly unwilling to engage Mr. Leahy on whether a president had an “absolute right” to pardon himself, as Mr. Trump has claimed that he does.
“That question may or may not arise, but that is one that calls for legal analysis of what the scope of the pardon power is,” she said, adding that she could not offer an opinion on a question that she could be called upon to rule on.
A frustrated Mr. Leahy asked one more, this time focusing on the Constitution’s emoluments clause, which is meant to limit foreign influence on the president by prohibiting him from accepting foreign gifts.
Citing news reports, Mr. Leahy asked if the tens of millions of dollars in business done by Mr. Trump’s hotels and clubs with foreign entities fell under that clause.
Again, no answer from Judge Barrett.
“As a matter being litigated, it’s very clear that is one I can’t express an opinion on, because it could come before me,” she said.
Soon after Wednesday’s hearing started, Americans got a brief tutorial on the legal doctrine of severability from Judge Barrett, elicited by Republicans on the panel.
The point was to signal that the Affordable Care Act may not be in peril when the Supreme Court hears arguments next month on the fate of the law, often called Obamacare. Democrats have focused relentlessly on the threat to the law as they have made their case against Judge Barrett, who they warn would join a 6-3 conservative majority to strike it down.
Even as Republican state officials and the Trump administration are asking the Supreme Court to invalidate the entire Affordable Care Act based on what they say is a flaw in a single provision of the sprawling law, Mr. Graham asked Judge Barrett to describe severability.
She said the doctrine generally requires that courts strike down a single provision of a law and retain the balance of it.
“The presumption,” Judge Barrett said, “is always in favor of severability.”
That is the key issue in next month’s case. After Congress zeroed out the penalty for not obtaining insurance in the so-called individual mandate, Republican state officials argued that the mandate was now unconstitutional. They added, more significantly, that this meant the entire law must fall, including protections for pre-existing conditions.
Judge Barrett did not say how she would vote in the pending case, but the general tenor of her summary suggested that she was skeptical of the maximalist arguments made by Republican officials.
Her general statement was consistent with an opinion in July from Justice Brett M. Kavanaugh, Mr. Trump’s last nominee.
“Constitutional litigation is not a game of gotcha against Congress, where litigants can ride a discrete constitutional flaw in a statute to take down the whole, otherwise constitutional statute,” Justice Kavanaugh wrote.
During Tuesday’s confirmation hearing, Senator John Kennedy, Republican of Louisiana, asked Judge Barrett about her views on climate change. “You know, I’m certainly not a scientist,” she said, and added that “I have read things about climate change — I would not say I have firm views on it.”
Her language may have sounded familiar to anyone who has watched Republican lawmakers wrestle with their party’s longstanding disavowal of climate science: While party stalwarts used to simply deny that human activity is causing the planet to warm dangerously, they increasingly have taken the more neutral “I’m not a scientist” position.
“It’s a dodge that fails to acknowledge the overwhelming scientific consensus that humans are causing the planet to warm,” said Ann Carlson, a faculty director of the Emmett Institute on Climate Change and the Environment at U.C.L.A. School of Law, who said she found Judge Barrett’s statement “disturbing.”
She continued, “Judge Barrett is a smart, highly educated person who has spent most of her career in a job that rewards knowledge and intellect. For her not to have firm views on climate change is almost unbelievable.”
The evidence that the planet is warming, and that warming is having destructive effects, has only grown more pressing as more and more Americans have come to understand the links between extreme weather in their own lives — including more destructive hurricanes and wildfires. The issue is increasingly important to voters, and has become a prominent part of the presidential race; President Trump has continued to scoff at the evidence underlying climate change, even saying recently that “I don’t think science knows, actually,” while Joseph R. Biden Jr. promises an aggressive $2 trillion plan to counter global warming.
It is also important to the Supreme Court. In past decisions, the justices have accepted that human-caused climate change is occurring and determined that the Environmental Protection Agency can regulate greenhouse gases in the case Massachusetts v. E.P.A., but a more conservative Supreme Court might revisit the issue.
To Professor Carlson, Judge Barrett’s seemingly anodyne answer “seems like a pretty strong signal to those in the know that she is skeptical of regulating greenhouse gases.”
Mr. Graham, who is fighting off an increasingly steep re-election challenge from a Black Democrat in South Carolina, drew criticism on Wednesday after he invoked the “good old days of segregation” while questioning Judge Barrett.
Asking the judge about various Supreme Court precedents as he opened the third day of hearings, Mr. Graham appeared to be trying to drive home the point that there was no longer any meaningful push in America to challenge the 1954 Brown v. Board of Education decision, which held that school segregation was unconstitutional.
“One of the reasons you can say with confidence that you think Brown v. Board of Education is a super precedent is you are not aware of any effort to go back to the good old days of segregation via legislative body. Is that correct?” he asked. Judge Barrett answered in the affirmative.
As Judge Barrett has done, Mr. Graham contrasted that decision to precedents like the one in Roe v. Wade, which enshrined a federal right to an abortion, and which has been a frequent target of legal challenges stemming from state laws rolling back abortion rights.
But the chairman’s comment drew a swift rebuke from his Democratic rival, Jaime Harrison, who shared a clip of Mr. Graham’s remark on his Twitter account, sending it bouncing across social media.
“The good old days for who, Senator?” Mr. Harrison asked. “It’s 2020, not 1920. Act like it.”
During a break in the hearing, Mr. Graham said he had been misunderstood and rebuked his opponent for the criticism. His comments were “dripping with sarcasm,” Mr. Graham said, referring to the era of segregation as “dark days.”
“It blows my mind that any rational person could believe that about me,” he added.
The comment came just a few days after Mr. Graham was roundly criticized for saying during a campaign forum in South Carolina that Black people “can go anywhere in this state” as long as they were “conservative, not liberal.”
He had been talking about his friendship with the state’s other Republican senator, Tim Scott, who is a Black man.