The Supreme Court has ruled against Kim Dotcom in his bid to gain access to evidence the US government has against him in his extradition case.

Dotcom took his extradition fight to the Supreme Court mid last year.

Dotcom's lawyer, Paul Davison, was seeking disclosure of all relevant evidence collected in the case, saying it is imperative to a fair hearing.

The Crown, on behalf of the US, says he should have access only to a summary called a "record of case".

The US is seeking to extradite Dotcom to face charges of copyright conspiracy, racketeering and money-laundering allegedly carried out by his file-sharing company, Megaupload.

The matter of disclosure has already been ruled on in three courts. Two judges - one in the District Court and one in the High Court - ruled that Dotcom should be allowed to see all the information, but this year the Court of Appeal ruled against him.

The Supreme Court - the final say - ruled by a majority today that the District Court was wrong in its ruling to order disclosure. 

The Extradition Act did not require full disclosure.

There is a duty of "candour and good faith" on the country seeking extradition, in this case US, but there is no suggestion the US did not comply with this requirement.

The Supreme Court said the District Court had no statutory power and no inherent power to rule towards disclosure.

The appeal was dismissed in a majority decision, with Chief Justice Sian Elias dissenting.

Dotcom's first reaction to the decision was to tweet a sad face. He has since vowed to fight on.

The German-born internet mogul was arrested in 2012 following a police raid on his Coatesville mansion, north of Auckland.

Being defeated is often a temporary condition. Giving up is what makes it permanent.

— Kim Dotcom (@KimDotcom) March 20, 2014

It's disappointing that we lost in the Supreme Court by majority decision. But great that Chief Justice of NZ would have allowed our appeal.

— Kim Dotcom (@KimDotcom) March 20, 2014

- Stuff