(CNN)Internet mogul Kim Dotcom has lost another fight in his epic legal battle to avoid being extradited to the United States.
An appeals court in New Zealand on Thursday rejected Dotcom's attempt to overturn an earlier ruling which said he should face criminal charges in US, saying Washington had made a "clear prima facie case to support the allegations that the appellants conspired to, and did, breach copyright willfully and on a massive scale for commercial gain."
Dotcom is the flamboyant founder of file-sharing site Megaupload, which was shut down by the US government in 2012. He was arrested soon after by New Zealand police who descended on his luxury mansion in Auckland in two marked helicopters, and had to cut their way into a locked safe room to reach him.
The decision whether to extradite Dotcom now rests with New Zealand's Justice Minister Andrew Little, however Dotcom has indicted he'll apply for leave to appeal Thursday's ruling at New Zealand's Supreme Court.
Along with three co-defendants, Dotcom was indicted by a US grand jury on a range of charges including conspiracy to commit racketeering, wire fraud, conspiracy to infringe copyright on a commercial scale and money laundering.
They deny the accusations and have been fighting hard against extradition, arguing that Megaupload was simply a file-sharing website and that they shouldn't be blamed for what others were uploading to it.
Three New Zealand courts have now ruled against them, throwing out that argument and claims that they couldn't be extradited on charges of profiting from copyright infringement because it is not a crime in New Zealand.
While the Court of Appeal held that "double criminality" was required for an extradition offense, it said that "we are satisfied that New Zealand law permits extradition for copyright infringement in the circumstances of this case."
"The appellants are accused of conduct that, if proved, would establish extradition offenses in New Zealand law," the court said.
Dotcom also lost an attempt at the US Supreme Court to recover $40 million of assets seized by the government.
New Zealand's Justice Ministry declined to comment on the ruling Thursday, however under the country's Extradition Act, Justice Minister Little has final say on the matter.
Ira Rothken, Dotcom's US-based lawyer, said on Twitter the defendants were "disappointed with today's judgment by the NZ Court of Appeal."
"We have now been to three courts each with a different legal analysis -- one of which thought that there was no copyright infringement at all," he said. "We will seek review with the NZ Supreme Court."
Per New Zealand law, only the Supreme Court decides which cases it will hear and Dotcom's legal team will now have to apply for leave to appeal.
In a statement, Dotcom said his legal team was "confident that the Supreme Court will hear the appeal given there are such significant legal issues at stake."
He said the Court of Appeal judgment was "in complete denial of the legislative history and intention of the Copyright Act. Therefore it has the value of toilet paper."
"The precedent set is concerning and has ramifications in New Zealand outside my case," Dotcom added. "The decision exposes Internet Service Providers to criminal liability for the misuse of their services by users, as is claimed against me."
US law is heavily weighted in favor of copyright holders, and has been criticized for stifling innovation and harming consumers, and for exporting US copyright regulations to other countries through free trade agreements.
Washington has also gone aggressively after file-sharing websites, with multinational cases against Kickass Torrents and The Pirate Bay. Defenders of the site point to the fact that they merely facilitate breach of copyright by sharing links to peer-to-peer torrent downloads, and do not actively host any protected files.