Donald Trump’s former strategist Steve Bannon is expected to ask a federal appeals court to overturn his contempt of Congress conviction, contending that he should have been allowed at trial to argue he defied a subpoena from the House January 6 select committee on the advice of his lawyers.

The appeal will seek the DC circuit court to quash the conviction for which he is set on Friday to face a potential six month prison sentence and $200,000 in fines as recommended by the justice department, according to sources familiar with the matter.

Bannon’s appeal is expected to make the case that the legal precedent that prevented US district court judge Carl Nichols from allowing his lawyers to argue the definition of “willful” defiance used at trial, as well as the fact that he had relied on the advice of counsel, was inapplicable.

The argument appears to capitalize on repeated acknowledgements by Nichols in pre-trial rulings that he considered the legal precedent to be outdated and might have otherwise permitted Bannon’s lawyers to say the former aide – because of bad legal advice – did not realize he acted unlawfully.

“I think that the DC Circuit may very well have gotten this wrong,” Nichols said. “The problem is, I’m not writing on a clean slate here.”

Bannon’s appeal is expected to echo points raised in his sentencing memo, which complained that the precedent set by the DC circuit in Licavoli v United States 1961 – that the justice department merely had to prove Bannon intentionally defied the select committee subpoena – was outdated.

The definition of “willful” for contempt of Congress prosecutions has changed since the ruling in the Licavoli case, the memo noted, and the supreme court recently has said prosecutors have to show defendants knew their conduct was unlawful in order to prove they willfully violated a statute.

That should have been the standard for Bannon’s trial, the memo argued, suggesting that would have paved the way for Bannon to make the case that he did not believe defying the subpoena was unlawful after his lawyers told him he was protected by executive privilege.

Bannon could face an uphill struggle with his appeal. Even if the precedent was updated, legal experts said, Bannon would still have to defend against the justice department and the select committee’s argument that Trump never actually asserted privilege for his former strategist.

And even if Bannon could produce correspondence to show Trump had asserted executive privilege – to date, there has only been an email from his lawyer appearing to make that assumption – he would have still needed to attend the deposition and assert it question by question, the experts said.

A spokesman for Bannon declined to comment.

Bannon was charged with two counts of contempt of Congress after his refusal to comply at all with the select committee’s subpoena demanding documents and testimony last year triggered the House of Representatives to refer him to the justice department for prosecution.

The select committee had sought Bannon’s cooperation after it identified him early on in the investigation as a key player in the run-up to the Capitol attack, who appeared to have advance knowledge of Trump’s efforts to stop the certification of Joe Biden’s election win on January 6.

Among other moments of interest, the Guardian has previously reported, Bannon received a call from Trump the night before the Capitol attack while he was at a Trump “war room” at the Willard hotel and was told of then vice president Mike Pence’s resistance to decertifying Biden’s win.

The close contacts with Trump in the days and hours leading up to the Capitol attack meant Bannon was among the first targets of the investigation, and his refusal to comply with the subpoena galvanised the panel’s resolve to make an example of him with a contempt referral.

During the five-day trial in July, Bannon’s legal team ultimately declined to present any evidence in defense after Nichols excluded the “advice of counsel” argument, and the justice department told the jury in closing arguments they should find the case straightforward.

“The defense wants to make this hard, difficult and confusing,” assistant US attorney Amanda Vaughn said in federal court in Washington. “This is not difficult. This is not hard. There were only two witnesses because it’s as simple as it seems.”

That meant the only arguments left available to Bannon were either that he was somehow confused about the deadlines indicated on the subpoena, or that he did not realize the deadlines were concrete and failing to comply with those dates would mean he was in default.