Kim Dotcom's lawyer has accused the Crown of mis-translating the mogul's communications to demonise him in international headlines.

Ron Mansfield has opened his case in defence of the internet entrepreneur at the extradition hearing before Auckland District Court this morning.

The FBI laid charges in January 2012 when Dotcom and three others - Mathias Ortmann, Bram van der Kolk and Finn Batato - were indicted on 13 charges including copyright infringement, racketeering, money laundering and fraud.

Throughout the Crown's case on behalf of the US government, which was heard during the first fortnight of the hearing, Christine Gordon, QC, made numerous references to conversations between Dotcom and his co-defendants.

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The communications - predominantly via Skype and in German - were used to push the US case that the men knew Megaupload was being used frequently to spread copyright-infringing material.

But Mr Mansfield said the Crown gave a "prejudicial and fundamentally biased picture of the case".

The "rot", he said, ran deeper too.

He accused the opposing legal team of incorrectly translating some of Dotcom's messages.

"At some point a judge will be convinced about how evil we are and then we are in trouble," Dotcom was accused of writing.

However, Mr Mansfield had the passage translated by three independent academics, who found a much different meaning in the words.

"Because at some stage a judge will be talked into how bad we allegedly are and then it will be a mess," was their interpretation.

The defence lawyer said the sentence had been mentioned four times by the Crown during their submissions "with the knowledge that it would make international media headlines".

A dozen stories from around the world were shown on big screens in the courtroom to emphasise his point.

Mr Mansfield said Dotcom had never called the US home or intended to, nor had he ever operated a business from there.

To say extradition would have a significant impact was "a gross understatement", he said.

He urged Judge Nevin Dawson not to simply rubber stamp the US's bid to extradite his client and to look past the "fanfare, propaganda and spin".

This morning he submitted that those behind Megaupload should be legally protected from prosecution under the Copyright Act because they were an internet service provider.

"Internet giants like Google, Facebook and Twitter are immune from prosecution and to indict them would result in unprecedented public outrage," Mr Mansfield said.

He suggested Megaupload -- fronted by the German national, with his "flamboyant and extravagant reputation" -- was not so immune.

Mr Mansfield is expected to spend the next four days detailing the case for Mr Dotcom.

Translation of Dotcom's message:

"At some point a judge will be convinced about how evil we are and then we are in trouble" (Crown translation)

"Because at some stage a judge will be talked into how bad we allegedly are and then it will be a mess" (Defence translation, peer reviewed by three interpreters)