Ex-MP John Banks has failed in his bid to recoup costs of $190,000 after he cleared his name in relation to electoral-fraud charges.

The matter came before the High Court at Auckland last week where Banks' counsel David Jones, QC, said his client had suffered a "grave injustice" and was "seeking justice for a level of recompense for costs incurred in this court".

The lawyer said the Crown had exhibited a "blinkered approach" in terms of the prosecution and he made reference to "perjured evidence".

"Clearly the evidence was false by [Kim] Dotcom, [Mona] Dotcom and indeed [Dotcom's former bodyguard Wayne] Tempero. It can't have been true," Jones said.


But Justice Edwin Wylie said he did not accept the matter was that simple.

"Mr Dotcom and Mrs Dotcom and Mr Tempero have not been charged with perjury, insofar as I am aware, and it cannot be baldly asserted that their evidence, and Mr Tempero's evidence, was fabricated," he said.

Banks' original conviction was essentially based on the judge preferring the Dotcom's evidence over that of Banks' wife Amanda, but the Court of Appeal overturned that after she tracked down US witnesses who corroborated her story.

"The significance of the American businessmen's evidence only became apparent once it was obtained and when Mr Dotcom accepted that it was correct," Justice Wylie said.

"Only then was the reliability of Mr Dotcom's, Mrs Dotcom's and Mr Tempero's evidence at trial thrown into question, and only then did the Crown case start to unravel."

Last week, Banks told the Herald he believed the Crown had deliberately tried to blacken his reputation.

He called it "vindictive, obstructive and in the end blatantly dishonest".

Justice Wylie disagreed.

"In my view, the Crown's investigation into the offence charged was conducted in a reasonable and proper manner, and by reference to the material which was before it at all relevant times," he said.

"Mr Banks has to bear some responsibility for what had occurred at trial and in my judgment his behaviour in regard to the proceedings does not support an award of costs in his favour."

The judge took the unusual step of publicly apologising to Mrs Banks in court last week after he rejected her evidence in his original judgment.

He reiterated those sentiments in his written decision released today.

"Based on what I now know, I accept that I was in error when I made an adverse finding as to Mrs Banks' credibility in relation to the matters I have noted above. I appreciate that my finding will have upset her and caused her significant embarrassment and distress. This distress was, no doubt, compounded by the considerable media coverage given to the trial and to my Reasons for Verdict judgment. It is appropriate that I should acknowledge my error, and I do so," Justice Wylie said.

The original case related to donations Banks received from Dotcom for his 2010 Auckland mayoral campaign that were not disclosed on his electoral return and which he claimed were anonymous.

The Court of Appeal quashed his conviction after Mrs Banks' leg work.

In March, Banks was awarded $66,200 in costs from the Crown for the Court of Appeal hearings that resulted in his acquittal.