Media playback is unsupported on your device Media caption Strict voting laws affect millions of Americans

The US Supreme Court will hear a challenge to a key section of the Voting Rights Act, a law adopted to prevent discrimination at the polls.

It will hear an Alabama challenge to the requirement that states with a history of racial bias seek permission before changes to voting rules.

The move comes shortly after President Barack Obama's re-election.

Latino and African-American voters played a key role in the election, reflecting a shift in US demographics.

Arguments in the case are expected be heard by the Supreme Court in early 2013, with a decision expected by the end of June.

'Jim Crow time-warp'

The Voting Rights Act is seen as a key plank of civil rights era legislation. It was re-authorised in its entirety for 25 years in 2006 on a widely bipartisan vote in both houses of Congress.

Image caption The court has heard previous voting rights cases but not ruled directly on the law's constitutionality

The US top court now says it will decide on whether or not Congress exceeded its authority.

The section under review calls for "pre-clearance" - requiring certain states and local governments, mostly in the South, to receive federal approval before making any changes to their voting laws.

Opponents of section five say that the provision is out of date and is an over-reach of federal power.

"The America that elected and re-elected Barack Obama as its first African-American president is far different than when the Voting Rights Act was first enacted in 1965," Edward Blum, director of the Project on Fair Representation, which opposes race-based policies and spearheaded the suit, said in a statement.

"Congress unwisely reauthorised a bill that is stuck in a Jim Crow-era time warp,"

But supporters of the law said recent attempted changes to elections around the country, including a raft of new voter ID laws, showed exactly why the measure was still needed.

"Given the extensive voter suppression we've seen around the country, I think Section five's relevance could not be clearer," said Elise Boddie, litigation director for the National Association for the Advancement of Colored Peoples (NAACP)'s Legal Defense Fund

Backers of the provision say minority voters are less likely to have the types of photo ID needed to comply with the new laws.

A lower appeal court agreed, upholding section five via a 2-1 decision. The court said Congress had enough evidence of recent racial discrimination to justify renewing the law in 2006.

Racial discrimination in voting is "one of the gravest evils that Congress can seek to redress", appeal court judge David Tatel wrote in the majority opinion.

The Supreme Court avoided directly ruling on part of the law's constitutionally in a 2009 case, but suggested that the requirement may no longer be needed.