Washington ? Elena Kagan worked behind the scenes at the Supreme Court as a clerk, and stood at the lectern as solicitor general representing the government of the United States.

So it is not surprising that when she took her spot at the end of the mahogany bench Monday as the newest justice, Kagan, 50, seemed right at home.

She waited a respectful period as colleagues asked questions, then dived into a complicated and murky bankruptcy case in which the court’s best option, Chief Justice John Roberts noted, might be to choose the less “absurd” result.

Kagan’s debut, brief as it was, was the highlight of the court’s first day of its 2010-2011 term. Because of her work as solicitor general, Kagan was recused from the court’s second case of the day, and she will be absent more than present during its first two-week session. She will hear only four of 12 cases.

The court announced Monday that it declined to accept about 2,000 petitions that were among the cases that had accumulated during its summer break. Included in the group: whether school districts can ban religious music at events; what kind of records the National Security Agency may be forced to produce; and whether the University of Southern California owns the trademark “SC” or if the University of South Carolina can use it as well to sell baseball caps (lower courts sided with the Los Angeles school).

The court showed interest in a case in which civil detainees at Abu Ghraib prison in Iraq allege abuse by private companies that contract with the military. A panel of the U.S. Court of Appeals for the District of Columbia said the contractors cannot be sued under the 1789 U.S. Alien Tort Statute.

The court said the statute generally may not be invoked against private parties. The justices asked Acting Solicitor General Neal Katyal for the government’s view and whether it should accept the case.

In the bankruptcy case, Ransom vs. FIA Card Services, the justices considered ambiguous wording in the bankruptcy law. It appears to give a debtor a way to shield some income by deducting car “ownership costs,” even if the car is paid for.

The law gave Jason Ransom, who owed more than $80,000 in credit card debt, an ownership expense of $471 a month. That would add up to about $28,000 in shielded income over the course of his five-year payment plan.

Some justices, Kagan included, did not understand how a person who owned a car could receive the same break as someone paying off a loan or leasing a car.

Roberts, on the other hand, said paying even a dollar on car payments would allow the debtor to receive the whole monthly benefit, since the benefit was not based on actual costs but an average of others making car payments.

“So your argument leads to a result that is just as absurd as your colleague’s result on the other side,” Roberts told lawyer Deanne Maynard, representing the credit card company

“I don’t believe so, your honor,” Maynard replied.

Kagan sat farthest from Roberts’ right on the bench, the traditional spot for the most junior justice. President Barack Obama’s first nominee, Justice Sonia Sotomayor, sat at the other end.