The Supreme Court is handing down eagerly awaited rulings on gun rights and three other remaining cases in its last meeting until the fall and the final day of Justice John Paul Stevens' long service.
The justices could decide that the Second Amendment's right to "keep and bear arms" serves as a check on local and state gun control laws, as well as federal restrictions.
The court also could strike down part of a 2002 corporate reform law that was enacted in response to scandals at Enron Corp. and other companies.
The other remaining cases involve patents and a Christian group that bars gay students and wants official recognition from a state university.
The 90-year-old Stevens announced his retirement in April, paving the way for President Barack Obama to nominate Kagan to replace him. Kagan's hearing begins early afternoon in Washington, in a Senate hearing room a short walk from the court.
Stevens' retirement will take effect on Tuesday, after 34 years, six months and 11 days as a justice.William Douglas has the record, with more than 36 years on the Supreme Court.