How did we get here?published at 16:14 Greenwich Mean Time 6 February
US Special Counsel Jack Smith has charged Donald Trump with conspiring to overturn Joe Biden's victory in the 2020 election and committing fraud to stay in office.
The trial in that case was initially scheduled for 4 March, but was postponed pending a ruling on the immunity claim.
Last month, a panel of three judges heard the case at the US Court of Appeals for the DC Circuit.
The argument from Trump's lawyer hinged on the idea that a president who is not convicted for impeachment by Congress cannot be subject to criminal proceedings.
Trump, they noted, was impeached by the House of Representatives but never convicted by the Senate.
The judge presiding over the trial had already rejected this argument in December.
Judge Tanya Chutkan wrote at the time that the presidency "does not confer a lifelong 'get-out-of-jail-free' pass".
At the hearing, the judges - two Democratic appointees and one Republican appointee - were sceptical of the former president's argument.
One, Judge Florence Pan, suggested that immunity would allow a president to sell state secrets or order the assassination of a political rival without being concerned about criminal prosecution.