Should Kim Dotcom be allowed to see the evidence the U.S. government intends to use against him in his upcoming copyright infringement trial? A New Zealand District Court said yes last year, as did the High Court, but the Court of Appeal decided otherwise so Dotcom's legal team is challenging that ruling in the Supreme Court today. The outcome will be of great importance to the Internet entrepreneur.

Following the arrest of Kim Dotcom and his associates in New Zealand in January 2012, it quickly became clear that the United States government would seek to extradite them to face copyright infringement, racketeering, money laundering and sundry other charges.

Understandably, Dotcom’s legal team wishes to contest the U.S. version of events so that Dotcom can remain a free man in New Zealand, but to do that they would need access to the evidence gathered by the United States during its Megaupload investigation. To this day the U.S. government insists that no such right of disclosure exists.

The battle to see those documents has already taken more than a year. In May 2012, a judge in the North Shore District Court ordered disclosure of all documents relating to the alleged crimes of the so-called Mega Conspiracy.

That decision was subsequently challenged and in August 2012 a High Court judge dismissed an application for judicial review and upheld the earlier ruling of the District Court. But the celebrations for Dotcom and co-accused Finn Batato, Mathias Ortmann and Bram van der Kolk didn’t last. The case went to the Court of Appeal where it was decided that all the U.S. had to do was show there is a prima facie case to answer.

An appeal of that ruling, this time by Dotcom, means that today the case is being heard at the Supreme Court in Wellington by a panel of five judges.

Paul Davison QC, counsel for Dotcom, told Chief Justice Dame Sian Elias and Justices Susan Glazebrook, William Young, John McGrath and Terence Arnold, that under the law Dotcom is entitled to a fair trial. That, he said, was being undermined by Dotcom not having access to the evidence against him.

The Crown says that Dotcom can hear that evidence as part of his trial in the United States, but Davison said if things go to plan, that stage will never be reached.

“If matters proceed the way Mr Dotcom would have them, there will not be a US phase,” Davison said.

Davison argued that the New Zealand/United States extradition treaty doesn’t prevent disclosure of evidence greater than the summary currently being provided and that since the documents are stored digitally, they could easily be sent. The current case summary runs to 109 pages but Davison says more crucial detail is required.

However, Crown lawyer Mike Heron, who is acting on behalf of the United States, said that any disclosure would only lead to further requests from Dotcom to see more and more of the evidence. Furthermore, Heron said that the argument that a fair trial would not be possible without further disclosure is one that had been tested many times during the past 20 years and had failed every time. Additional disclosure would only slow down the extradition, Heron said.

Dotcom’s legal team, on the other hand, feel that the level of disclosure so far falls short of that already allowed by the Extradition Act. Davison further argued that the U.S. case has a number of core problems, not least that it fails to show that Dotcom and his associates had criminal intent in their activities at Megaupload.

The Supreme Court will now have the final say on the issue. Dotcom’s extradition hearing is now expected to go ahead in November.