FACTBOX: Campaign finance, other cases before U.S. top court

(Reuters) - The U.S. Supreme Court, with new Justice Sonia Sotomayor, holds a special session on Wednesday to consider ending long-standing limits on corporate and labor union spending in U.S. political campaigns.

The case stemmed from a conservative advocacy group's challenge to a federal campaign finance law as part of its effort to broadcast and promote a movie critical of Hillary Clinton during her presidential campaign.

Supporters of the limits said the court could unleash a flood of corporate and union money into the U.S. political system to promote or defeat candidates.

The rearguments in the case occur about a month before the opening of the Supreme Court's new term. It will be the first case heard by Sotomayor, who was approved by the Senate in August after she was nominated by President Barack Obama.

Other cases to be argued and decided during the term include:

JUVENILE JUSTICE

* Whether a sentence of life in prison for juveniles who commit crimes other than murder violated the constitutional ban on cruel and unusual punishment.

The ruling could affect more than 2,500 people in the United States serving sentences of life imprisonment for crimes committed before they turned 18, human rights groups said.

The two Florida cases the Supreme Court will hear and decide involve a 13-year-old convicted of raping an elderly woman and a 17-year-old who took part in an armed home-invasion robbery while on probation for an earlier violent crime.

ANIMAL TORTURE VIDEOS

* Whether a federal law that makes it a crime to sell videos of animals being tortured or killed violated constitutional free-speech rights.

The U.S. Justice Department defended the 1999 law that Congress adopted in an effort to crack down on videos like those depicting dog fights. It compared animal cruelty to child pornography, which the Supreme Court has said does not qualify for free-speech protection.

SEX OFFENDERS

* Whether Congress may adopt a federal law that keeps sex offenders in custody indefinitely after they complete their prison sentences. Similar state laws have been upheld.

PATENT CASE

* A closely watched patent case, important to the business community, that could tell high-tech and software companies how far they can go in patenting software, financial strategies and other abstract processes. The case has implications for any company that hopes to patent a business method.

ACCOUNTING BOARD

* A constitutional challenge to the 2002 law that created a national board to oversee U.S. public company auditors. The justices will decide a key provision of the Sarbanes-Oxley Act, which set up the private sector Public Company Accounting Oversight Board.

Those challenging the law argued it violated constitutional requirements on separation of powers because it failed to allow adequate control of the board by the U.S. president.

(Reporting by James Vicini; editing by Mohammad Zargham)