Washington (AFP) - The US Supreme Court agreed on Wednesday to hear a challenge to the use of a law behind one of the charges lodged against former president Donald Trump and hundreds of his supporters who took part in the 2021 attack on the Capitol.

The case, which will be heard by the nation's highest court next year, could potentially delay Trump's upcoming trial for allegedly conspiring to overturn the 2020 election results.

Trump, the frontrunner for the 2024 Republican presidential nomination, is scheduled to go on trial in March and his lawyers have been seeking to postpone his trial until after the November 2024 election.

The timing of this Supreme Court case could have an impact on that calendar.

The law in question -- obstruction of an official proceeding -- is among the charges filed against Trump related to the violent disruption by Trump backers of the January 6, 2021 congressional certification of Democrat Joe Biden's election victory.

Joseph Fischer, an ex-police officer who is among more than 300 Trump supporters also charged with obstruction, has sought to get the charge dismissed, which could have a knock-on effect for all the cases -- including Trump's. A conviction under that charge would carry a maximum sentence of 20 years in prison.

A District Court judge, a Trump appointee, agreed to throw out the obstruction charge on the grounds that the law was intended to prosecute financial crimes following the Enron scandal and did not apply to Fischer's conduct on January 6.

That ruling was reversed by a federal appeals court in a 2-1 decision.

Now the Supreme Court, which has a 6-3 conservative majority, including three justices nominated by Trump, will hear Fischer's appeal next year and is expected to issue a ruling by the end of its term in June -- around four months before the November 4 presidential election in which Trump is expected to face Biden again.

'Absolute immunity'

Special Counsel Jack Smith, who brought the election interference case against Trump, asked the Supreme Court earlier this week to rule on whether the former president has immunity from prosecution.

Trump's lawyers claim that a former president has "absolute immunity" and cannot be prosecuted for actions he took while in the White House.

US District Judge Tanya Chutkan, who is to preside over Trump's March trial in Washington, rejected the immunity claim earlier this month, a ruling appealed by Trump's attorneys.

Smith has asked the Supreme Court to bypass the appeals court and take up the immunity case itself on an emergency basis.

"Nothing could be more vital to our democracy than that a President who abuses the electoral system to remain in office is held accountable for criminal conduct," the special counsel said.

Judge Chutkan, in an opinion issued on Wednesday, said she was pausing all proceedings in the election interference case pending the outcome of Trump's immunity appeal.

Trump was indicted in August for conspiracy to defraud the United States and two counts of obstruction for his efforts to upend the results of the 2020 election won by Biden.

The former president is also accused of seeking to disenfranchise American voters with his false claims he won the election.

Trump and his two eldest sons are currently embroiled in a civil fraud case in New York, accused of inflating the value of their real estate assets to receive more favorable bank loans and insurance terms.

Trump additionally faces federal charges for alleged mishandling of top secret documents after he left the White House and has been indicted for racketeering in Georgia on accusations that he tried to overturn the 2020 election results in the southern state