By Andrew Chung

(Reuters) - The U.S. Supreme Court on Thursday agreed to decide whether a federal law barring trademarks on racial slurs violates free speech rights in a case involving an Oregon band called The Slants that could impact the high-profile dispute over the name of the NFL's Washington Redskins.

The justices said they would hear the Obama administration's appeal of a lower court ruling last year that sided with the Portland-based Asian-American rock band in its free-speech challenge to part of the 1946 law governing federal trademarks.

The Redskins have separately challenged the law, also arguing it violates the U.S. Constitution's First Amendment guarantee of free speech. The Supreme Court did not act on the Redskins case, meaning it could be held for further consideration or denied later.

John Connell, a lawyer for The Slants, said he was pleased with the court's decision to hear the appeal and looked forward to vindicating the band's First Amendment rights.

The Supreme Court will hear arguments and decide the case in its coming term, which begins on Monday and ends next June.

The cases began after the band and the team separately lost rulings at the U.S. Patent and Trademark Office. An agency tribunal refused to grant trademark protection for the band's name in 2013, saying it was offensive to people of Asian descent. Some consider the term "slant eye" a racist slur.

In the Redskins' dispute, the tribunal in 2014 canceled the team's six trademarks at the request of Native American activists on grounds that the team name disparaged Native Americans.

The tribunal relied on a provision of the 1946 Lanham Act that prevents the registration of marks that may disparage certain people.

In appealing to the U.S. Court of Appeals for the Federal Circuit in Washington, Slants front man Simon Tam argued the band adopted the name to reclaim the word slants as a "badge of pride."

The Federal Circuit ruled last December that the disparagement provision of the 1946 Lanham Act was unconstitutional. Though it might lead to more hateful trademarks in the future, the court said, the First Amendment forbids government from banning offensive speech.

In April, the federal government asked the Supreme Court to hear its appeal of the ruling in the band case, saying that if not overturned, the decision would permit trademarking "even the most vile racial epithet."

The administration said the law does not restrict speech because the disputed names may still be used without federal registration. Such registration, however, can help protect trademarks nationwide in court and block the import and sale of counterfeit goods.

Paul Fucito, a trademark office spokesman, and Redskins' attorney Lisa Blatt declined to comment.

The team, one of the National Football League's marquee franchises worth an estimated $2.4 billion, adopted the name Redskins in 1933 when it played in Boston before moving to Washington in 1937, and first trademarked the name in 1967.

A federal judge upheld the cancellation of the team's trademarks in July 2015. An appeal in the 4th U.S. Circuit Court of Appeals in Richmond, Virginia is pending, but the team has urged the Supreme Court to hear its case even before that court rules.

The cases in the Supreme Court of the United States are Michelle K. Lee v. Simon Shiao Tam, No. 15-1293, and Pro-Football, Inc v. Amanda Blackhorse et al, No. 15-1874.

(Reporting by Andrew Chung; Editing by Will Dunham)