The supporters of the former US president Donald Trump stormed Congress in Washington DC on 6 January of their own accord, say his lawyers in an attempt to defend their client against impeachment charges.
Trump was impeached for the second time by the House of Representatives last month on the charge of inciting insurrection. A trial in the Senate regarding the impeachment is due to begin on Tuesday, reports BBC
Trump who allegedly prompted the riot says he will not testify.
Five people, including a police officer, died when a mob of Trump supporters attacked the Capitol building, forcing politicians and staff to hide in offices.
Mr Trump is the only US president in history to have been impeached twice and one of only three to have been impeached at all.
In a pre-trial brief released on Monday, the former president's lawyers said that FBI documents had shown that the riot was planned days in advance, meaning that Mr Trump cannot have encouraged the violence.
They also insist the trial is unconstitutional because Mr Trump has left office and is now a private citizen.
They hit out at the nine "impeachment managers" - Democrats from the House of Representatives who will lay out the case for prosecution - accusing them of "intellectual dishonesty and factual vacuity" in the way they portrayed Mr Trump's address to his supporters.
"This impeachment proceeding was never about seeking justice," the lawyers wrote.
"Instead, this was only ever a selfish attempt by Democratic leadership in the House to prey upon the feelings of horror and confusion that fell upon all Americans across the entire political spectrum upon seeing the destruction at the Capitol on January 6 by a few hundred people."
What will happen on Tuesday?
The trial is expected to begin with a four-hour debate in the Senate and then a vote on whether the proceedings are unconstitutional, sources quoted by Reuters said.
If it proceeds - as it is expected to - debate will recommence on Wednesday afternoon.
However, for the Senate to convict Mr Trump a two-thirds majority is required meaning 17 Republicans would need to join the chamber's 50 Democrats in the vote.
On 26 January, a bid to dismiss the case as unconstitutional was backed by 45 of the Senate's 50 Republicans.