Ketanji Brown Jackson gave a passionate defense of her sentencing of child sexual abuse imagery offenders as a rebuttal to attacks from a Republican senator who has accused her of endangering children, as her confirmation hearings for a seat on the US supreme court entered a critical second day.

At the start of an epic day of questioning before the Senate judiciary committee on Capitol Hill, Jackson strongly rejected claims made by Josh Hawley, Republican senator from Missouri.

The senator has spent several days advancing the theory that the Biden nominee, in her eight years as a federal district court judge, handed down sentences that were far more lenient than federal guidelines suggested or prosecutors requested.

Hawley’s accusations have been debunked as misleading and false. On Tuesday, Jackson gave a personal response to the claims.

“As a mother and a judge who has had to deal with these cases, nothing could be further from the truth,” Jackson said under questioning from Dick Durbin of Illinois, the Democratic committee chair.

She said child abuse cases were among the most difficult she dealt with as a judge, and described child sexual abuse imagery as a “sickening and egregious crime”.

On the second day of hearings, each committee member was given 30 minutes to engage with Jackson. On Wednesday, they will get 20 minutes for follow-up questions. The final decision on confirmation will be made in a vote of the full Senate that is likely to be held by the first week in April.

After a relatively amicable opening day, Jackson was facing up to 12 hours on Tuesday of possibly grueling interrogation from the 22-member committee, half of which is Republican. If confirmed, Joe Biden’s nominee would become the first Black woman to sit on the nation’s highest court in its more than two centuries of existence.

At Durbin’s invitation, Jackson defended herself against the Republican attack line that she was soft in her legal approach to terrorist suspects held at the Guantánamo Bay military camp in Cuba. Jackson spent two years as a federal public defender and in that role represented some of the detainees in their bid for review of their cases.

Jackson pointed out that her brother, Ketajh Brown, joined the US military in the wake of the terrorist attacks on 9/11. But she went on to say that American justice required all defendants to be represented and treated fairly.

“That’s what makes our system the best in the world, that’s what makes us exemplars,” she said.

The committee also scrutinised amicus briefs filed by Jackson before the supreme court relating to Guantánamo. Lindsey Graham, Republican senator from South Carolina, focused on a brief that argued that detainees held there indefinitely as “enemy combatants” should either be put up for trial or released.

Graham said that if her argument had been accepted by the court it would have damaged the US war on terrorism. “This is not how you run a war,” he said.

Jackson replied that she had been conveying the views of the private groups and thinktanks that she had been representing, not her own opinions.

Graham also tried to impugn Jackson by association, pointing to progressive groups who had backed her nomination. He especially referred to groups that wanted to dilute conservative dominance of the supreme court by expanding the number of its justices.

“Every group that wants to pack the court, that believes this court is a bunch of rightwing nuts that is going to destroy America, that considers the constitution trash – all wanted you picked … That is problematic for me,” Graham said.

The nominee was asked by the committee to lay out her views on abortion. The subject is currently before the supreme court which is expected to dismantle the fundamental right to a termination enshrined in its own 1973 ruling Roe v Wade.

Jackson said that she agreed with two of Trump’s appointees to the court, Brett Kavanaugh and Barrett, when they said in their respective confirmation hearings that Roe was settled law. She added that she believed that stare decisis – the legal principle of sticking with the court’s past precedent – was “very important”.

John Cornyn, Republican senator from Texas, tried to puncture the stare decisis argument that Roe should be respected as established precedent by invoking Dred Scott, the 1857 supreme court ruling that stripped people of African descent of US citizenship, and Plessy v Ferguson, the 1896 ruling that approved racial segregation. “Thank goodness the supreme court has been willing to revisit its precedent, otherwise we’d still be living with Plessy and Dred Scott,” he said.

Cornyn quizzed Jackson on her views about same-sex marriage and whether it was legitimate for the supreme court to have declared gay marriage legal in 2015. She said the court had decided that marriage equality was a right under the equal protection clause of the 14th amendment.

Cornyn riposted that five unelected justices had created a new fundamental right ignoring the will of voters. “We five members of the supreme court are going to decide what the law of the land should be, and anyone who disagrees with me will be labeled a bigot.”