The Court of Appeal has reserved its decision on whether Kim Dotcom will receive disclosure from the United States government in their case against him.
Dotcom, 38, appeared in the court in Wellington today in front of Justices Terence Arnold, Ellen France and Christine French.
The US government had lodged an appeal against a ruling that required them to disclose all evidence in their internet piracy case against him in order for a fair extradition hearing.
Dotcom, Finn Batato, Mathias Ortmann and Bram Van Der Kolk are defending accusations of copyright infringement and money laundering.
The internet millionaire, his wife and other supporters sat in the front of the public gallery during the hearing that lasted much of the day.
He has won two previous hearings about the issue - the Auckland District Court first ruled in his favour and then in the High Court in Auckland, Justice Helen Winkelmann dismissed an application by the US to have that ruling reviewed.
In court today, Paul Davison QC, appearing for Dotcom, said the United States government was deliberately working against "natural justice'' by refusing to pass disclosure to Dotcom and his associates.
"It's very important in this case because Mr Dotcom is facing extradition to a country he is not a resident in or a fugitive of or has any particular affinity with.''
Before Dotcom's arrest, there were 66 million users worldwide of his file sharing website Megaupload and 50m visits to the site daily.
John Pike, appearing for the US, told the court there was a vast amount of evidence relating to Dotcom's extradition trial.
"There are millions of emails and items involved in the case.''
But Mr Davison said the US prosecution had already presented a selection of evidence to two juries but was still refusing to share any disclosure.
"Mr Dotcom has a powerful opponent,'' he said.
"The absence of documentation has created a situation where Mr Dotcom won't have natural justice.''
Mr Pike said the District Court did not have the power to order disclosure in an extradition case.
He said there was an intense focus on the procedures by the District and High Courts, and they had put the international dimension to one side.
New Zealand was obliged to carry out its obligations under the extradition treaties it had signed, he said.
Guyon Foley, appearing for Batato, Ortmann and Van Der Kolk, said his reaction to the argument that the disclosure exceeded the normal amount of disclosure normally passed over was "too bad''.
He said the New Zealand law allowed for disclosure to be made to defendants and that should be adhered to.
"We're dealing with the law and we're dealing with very serious things in terms of liberty and a very lucrative business that was cut off at the request of the United States.''
If disclosure was not allowed to his clients, the logical conclusion was that the extradition hearing would be nothing more than a "rubber stamp''.
Justice Arnold said that was probably going too far.
At the close of submissions, Justice Arnold said he hoped to be able to deliver a decision as soon as possible.
Outside court Dotcom said he believed the US case was "malicious'' but the New Zealand judicial system was fair.
"The only thing I'm nervous about is the ongoing delaying tactics by the US to use Crown law.''
He said the US government was trying to defend outdated business models.
"They're using the case to change the way the internet works.''
He said he was always surprised that he and his associates had been charged while sites like YouTube were still operating and running much closer to the law on copyright infringements.
He said the advice had had always received from his legal team was that the company was working within the law.
PM: 'I never run"
Earlier today, Prime Minister John Key said it was John Banks' decision to stay away from Parliament when Mr Dotcom visited yesterday, but his own rule was "I never run''.
Mr Key said he did not know why Mr Banks did not turn up in Parliament for Question Time yesterday when Dotcom was in the Public Gallery to watch questions about the donation he had made to Banks for the 2010 Auckland Mayoral race.
Asked if he believed Mr Banks should have shown up, Mr Key said that was Banks' choice "but I know what I do''.
Mr Key told Prime News that Dotcom's visit was "a PR stunt'' and he had faced similar issues with other people, such as the Popata brothers - Maori activists from Northland.
"I have a simple rule: I never run. As far as I'm concerned I front up and someone wants to be there, that's their choice but I for one am not changing my behaviour because someone wants to pull a PR stunt.''
But Mr Banks did make an appearance in Parliament today after being noticeably absent yesterday - and when asked today why he'd failed to show Mr Banks said, "I was out doing what I do best and that's raising funds - just joking,''
Yesterday his spokeswoman said Mr Banks had other commitments and didn't know Dotcom would be in Parliament.
Mr Banks would not comment on whether Dotcom's claims yesterday he knew him well were true.
"Everything that needs to be said has been said,'' said Mr Banks.
Dotcom said yesterday he was hurt by Mr Banks' denial their friendship and said he should stand down from his ministerial roles because he had misled the public.
Dotcom also said Prime Minister John Key's leadership should be under the spotlight.
"It's a very fragile majority. The balance of power is threatened by this whole John Banks affair. So I think the Prime Minister has had to make a choice; am I going to uphold ethical standards, or do I want to remain in power.''