The US Supreme Court limited the ability of lawmakers to take the racial make-up of a state into account when drawing voting maps, in a ruling that could reshape politics across the American south.

In a 6-3 decision, the conservative justices sided with a challenge to new districts in Louisiana that were created to comply with a landmark Civil Rights law meant to protect black Americans from racial discrimination.

The way courts have previously interpreted Section 2 of the Voting Rights Act, Justice Samuel Alito wrote in the court’s majority opinion, has sometimes forced states “to engage in the very race-based discrimination that the Constitution forbids”.

The group of mainly white voters challenging the law had argued that relying on race to create districts ran afoul of the US Constitution and suggested that the provision of the Voting Rights Act should be found unconstitutional in its entirety.

The court majority did not take that position, but its decision will make it significantly more difficult to successfully challenge legislative maps for diluting the voting power of racial minorities.

To prove a violation, Alito wrote, litigants will have to prove that legislators intentionally drew the maps to provide less opportunity to racial minority voters.

“The court’s decision will set back the foundational right Congress granted of racial equality in electoral opportunity,” Justice Elena Kagan wrote in her dissenting opinion.

The fight over voting maps has grown fierce in the last year, as Democrats and Republicans seek to carve out districts that could help them win congressional majorities.

The White House celebrated the ruling, calling it a “complete and total victory for American voters”.

“The color of one’s skin should not dictate which congressional district you belong in. We commend the court for putting an end to the unconstitutional abuse of the Voting Rights Act and protecting civil rights,” spokeswoman Abigail Jackson told BBC partner CBS.

Florida is currently in the process of redrawing its legislative maps in an effort to net Republicans more seats in the House of Representatives. This decision could allow the state to further disadvantage incumbent Democrats who represented districts with large minority populations.

Other Republican states, such as Tennessee and Mississippi, could also redraw their maps in the weeks ahead.

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