Dotcom, the co-founder of file-sharing website Megaupload, is accused by U.S. prosecutors of racketeering and money laundering by facilitating millions of illegal downloads of copyrighted material on his site. Dotcom says he cannot be held responsible for those who chose to make illegal downloads on his site.
An extradition hearing has been scheduled for March.
Dotcom had sought to examine documents in the case against him, while U.S. prosecutors argued discovery should be narrowly limited at the hearing.
In upholding the ruling Thursday, Judge Helen Winklemann said disclosing the documents would help encourage a fair hearing, which she said could still remain focused.