The US Supreme Court has upheld two voting laws in Arizona that opponents said discriminated against racial minorities, in a major decision that may make it more difficult to bring challenges to voting restrictions being enacted in states across the US.

The case, Brnovich v Democratic National Committee, centred on two voting provisions in Arizona. The first banned “ballot harvesting”, whereby third parties collect and drop off early voting ballots. The second led to the rejection of ballots that were cast in the wrong precinct.

In a 6-3 decision released on Thursday, America’s highest court rejected claims that the Arizona voting laws were discriminatory.

Samuel Alito wrote the opinion, joined by the five other conservative jurists on the nine-member bench: John Roberts, Clarence Thomas, Neil Gorsuch, Brett Kavanaugh and Amy Coney Barrett. Elena Kagan wrote the dissent, joined by the two other liberals, Stephen Breyer and Sonia Sotomayor.

Alito said neither law violated Section 2 of the Voting Rights Act, which prohibits any election regulation that “results in a denial or abridgment of the right of any citizen of the United States to vote on account of race or colour”.

“Arizona’s out-of-precinct rule enforces the requirement that voters who choose to vote in person on election day must do so in their assigned precincts. Having to identify one’s own polling place and then travel there to vote does not exceed the ‘usual burdens of voting’,” Alito wrote. “On the contrary, these tasks are quintessential examples of the usual burdens of voting.”

But Kagan argued the court had undermined Section 2 “and the right it provides”.

“The majority fears that the statute Congress wrote is too ‘radical’ — that it will invalidate too many state voting laws,” she wrote. “So the majority writes its own set of rules, limiting Section 2.”

US president Joe Biden said he was “deeply disappointed” by the decision and vowed to press on with efforts to protect and expand voting access. “In a span of just eight years, the court has now done severe damage to two of the most important provisions of the Voting Rights Act of 1965 — a law that took years of struggle and strife to secure,” he said in a statement.

The Voting Rights Act is a landmark law that was enacted by President Lyndon Johnson in 1965 during the civil rights movement.

Nearly half a century later, the Supreme Court struck down a central provision of the legislation — which required certain states and localities to have election changes approved by the federal government — in the 2013 decision, Shelby County v Holder.

The debate over voting rights has heated up since Shelby, and more recently, after Donald Trump claimed last year’s presidential election was rigged against him.

According to the Brennan Center for Justice at New York University, at least 14 states enacted 22 laws that restricted voting access between January 1 and May 14 of this year. At least another 61 bills with restrictive provisions are still being considered in 18 states.

Most of the voting restrictions are being pushed by Republican governors and state legislators. Democrats in Washington have sought to counteract those efforts by passing new federal voting laws.

One bill, the “For the People Act”, passed the Democrat-controlled House earlier this year but stalled in the Senate after failing to clear a 60-vote filibuster threshold. A separate piece of legislation, an update to the Voting Rights Act named for the late John Lewis, is expected to be taken up by the House later this year.

Republicans cheered Thursday’s ruling. Ronna McDaniel, chair of the Republican National Committee, said: “Democrats were attempting to make Arizona ballots less secure for political gain, and the court saw right through their partisan lies.”

The Brnovich ruling comes at the end of the Supreme Court’s term, the first since conservative Barrett joined the bench following the death of liberal Ruth Bader Ginsburg. Barrett’s confirmation tipped the balance of the court to 6-3, in favour of jurists appointed by Republican presidents.

While the court issued several unanimous decisions this year, and many that cut across ideological lines, the 6-3 ruling on voting rights is likely to revive concerns among progressives about the court’s composition. In a second 6-3 decision on Thursday, the conservative justices invalidated a California law that required tax-exempt charities to disclose their donors’ names and addresses.

Supreme Court justices are appointed by presidents to life terms, but their nominations must be confirmed by a simple majority of the US Senate.

Progressive activists have called on Breyer, the oldest justice, to step aside so US president Joe Biden can appoint another liberal to his seat. Breyer, 82, has not commented on the matter.