The return to judicial matters comes after weeks of heated debate over his confirmation in the wake of an allegation from California professor Christine Blasey Ford that he sexually assaulted her when they were high schoolers in suburban Maryland decades ago. Kavanaugh denied the accusation.
Speaking later on Monday afternoon Trump amplified his views about Kavanaugh's treatment by Democrats during the confirmation fight, when he gave a speech in Orlando, Florida before the International Association of Police Chiefs.
In the 1990s, before becoming a judge, Kavanaugh was part of special counsel Kenneth Starr's team that investigated Democratic President Bill Clinton.
"On behalf of our nation, I want to apologize to Brett and the entire Kavanaugh family for the bad pain and suffering you have been forced to endure", Trump said, sticking a shiv in Democrats and Christine Blasey Ford.
"Every American can be assured that I will be an independent and impartial justice", Kavanaugh said in the White House East Room after a ceremonial swearing-in.
Tuesday - Kavanaugh will join the bench for the first time. He claimed he was the first justice to have an all-female staff. "And I think it's really going to show you something come November 6", when the midterms are held, Trump added.More news: Chelsea legend John Terry announces retirement from football
Former president Barack Obama's two Supreme Court appointees, Justices Sonia Sotomayor and Elena Kagan, did not participate in oath ceremonies at the White House.
The ranking member of the House judiciary committee, Jerry Nadler of NY, has said his party would investigate the sexual misconduct allegations against Kavanaugh if the Democrats reclaim the majority in the chamber.
The Senate confirmed Kavanaugh in a 50-48 vote Saturday, when Mr. Trump was en route to Kansas for a "Make America Great Again" rally.
The other eight justices also were at the White House Monday. On Wednesday, the only other day of arguments this week, the court will hear another two hours of arguments.
The political theorist Jacob Levy points out that if all this were to happen, then the political aspirations and values of a minority of Americans will dominate or have gone a long way towards shaping the White House, the Supreme Court, and both houses of Congress. Levy posits that one can still fundamentally accept many countermajoritarian aspects of our system while also finding such an across-the-board outcome deeply troubling.
A petition to impeach Justice Kavanaugh has more than 150,000 signatures.
Democrat Jerrold Nadler, who is in line to chair the House Judiciary Committee if his party wins a majority in the mid-terms, said that he would be prepared to open an investigation into the top judge.