The Court of Appeal has now ordered a new hearing after Mr Banks' lawyer David Jones, QC, filed an application to recall its ruling in October after he received fresh material from the Crown about the contentious lunch at the Dotcom mansion.
"If this material had been before the Court of Appeal, which it should have been, it is submitted it would have been a critical factor not only on the substantive appeal but also in the decision whether to order a retrial or not," Mr Jones wrote in a separate application to the High Court.
The recall application is opposed by the Crown but Justice Ellen France, president of the Court of Appeal, has ordered that a transcript of the previous hearing be prepared.
The new hearing at the Court of Appeal has been scheduled for the end of April.
The undisclosed evidence in question is a memorandum written by lawyer Rowan Butler who was instructed by Crown prosecutor Paul Dacre, QC, to interview Kim Dotcom about the affidavits filed by the two American businessmen before the appeal hearing.
The pair said they arrived in New Zealand on June 5, 2010 and were taken to Dotcom's Coatesville mansion, where they had lunch with Mr and Mrs Banks and Mr and Mrs Dotcom. Nothing about electoral donations was discussed, according to their affidavits.
This is at odds with evidence given at the trial, where the Crown contended the lunch was held on June 9, 2010 and the presence of the Americans was denied by the Dotcoms, as well as their bodyguard Wayne Tempero.
The defence was able to prove at the trial there was no lunch on June 9, because Mr Banks was campaigning and Mrs Banks was at work.
In finding Mr Banks guilty, Justice Edwin Wylie said Dotcom was a good witness but was wrong about the date of the lunch and ruled it must have happened on June 5.
But when interviewed by Mr Butler about the new affidavits before the Court of Appeal hearing, Dotcom accepted the evidence of the US businessmen - including that donations were not discussed at the June 5 lunch. Instead, he said there was a second lunch - again on June 9 - at which the donations were discussed.
The interview with Dotcom was never disclosed to Banks' legal team before the Court of Appeal hearing. The newly disclosed material contradicts all the evidence given at trial by the Dotcom witnesses, wrote Mr Jones.
"It has never been part of the Crown case nor has there been any prior suggestion that there were two lunches within a matter of days of each other, at which both Mr and Mrs Banks were present," wrote Mr Jones.
"How the Crown can now properly pursue this prosecution in the circumstances is unknown ... the Crown case will accordingly have to be completely recast in a way which, with respect, is utterly untenable."
The story so far
April 2012 - Kim Dotcom's $50,000 of anonymous donations to John Banks' mayoral campaign in 2010 becomes public.
July 2012 - Police say they won't lay charges after investigation.
November 2012 - Graham McCready takes private prosecution against the Act MP.
October 2013 - Banks resigns as a Minister after Judge Phil Gittos rules he should stand trial.
June 2014 - Banks is found guilty after a High Court trial. He later resigns from Parliament.
November 2014 - Banks is successful in overturning the conviction in the Court of Appeal.
January 2015 - Solicitor-General Mike Heron, QC, confirms a new trial. Scheduled for July.
March 2015 - Banks' lawyer David Jones, QC, seeks to have charge dismissed after the late disclosure of new material from the Crown. Now seeking Court of Appeal to recall its ruling which ordered a new trial.
April 2015 - The case heads back to the Court of Appeal.
