"At the heart of the principles of natural justice is the ability to defend one's self without one's hands tied behind one's back.''
He said the there are some "bedrock principles'' at stake.
"It is not to be treated or acted upon as if it is a rubber stamp.''
He said the judge hearing Dotcom's extradition hearing should be hearing a full case, where the defence knew what the US Government was alleging against their clients.
Mr Davison said if that did not happen, the judge hearing the case could not carry out his or her function.
"That's lipservice to the judicial process and, in my submission, the law requires much more than that.''
Today's court hearing was a judicial review sought by the Crown on behalf of the US Government after the District Court ordered authorities to release documents to Dotcom and his lawyers.
John Pike, on behalf of the FBI for Crown Law, told the court there was nothing in law to compel the release of evidence.
He said it was telling that lawyers for Dotcom and his co-accused had not been able to put any extradition cases before the court where the prosecution had been forced to reveal their investigation files.
He said the documents would number in the hundreds of thousands. "It is voluminous''.
Mr Pike also said the extradition hearing would be limited to evidence that directly challenged the FBI evidence.
He said most of that would be done by filing evidence in written form, rather than having witnesses come to court to be cross-examined as in criminal trials.
Chief High Court judge Justice Helen Winkelmann has reserved her decision.
Outside court, Dotcom was asked if he would be seeking compensation after a favourable High Court ruling released last week found the police raid on his mansion was unlawful.
"At the moment the priority is to get access to our information so we can defend ourselves properly in the extradition hearing, and so far we are being kept from that and it is not good for us.''
Earlier today, the court was told how Dotcom could get the chance to tell the court what happened at his house when police landed in helicopters with search warrants.
In her decision last week, Justice Winkelmann found that search warrants used in January's raid were invalid because they did not adequately describe the allegations against the internet multi-millionaire.
She said the warrants, issued by the District Court, gave police authority to seize too wide a range of items.
However, Justice Winkelmann said a resolution was to be decided by lawyers from both sides. They have indicated that they will file a memorandum and it is likely there will be a further hearing on the matter.
Dotcom, Finn Batato, Mathias Ortmann and Bram van der Kolk were arrested in January after a request for assistance from the FBI.
The US says the men were behind the world's biggest criminal copyright violation through Dotcom's filesharing website Megaupload, which carried about 4 per cent of the world's internet traffic. The men deny the charges.
A further hearing on what evidence seized during the New Zealand raids should be disclosed to Dotcom's lawyers ahead of an extradition hearing next month is now taking place.
