The UK High Court dismissed Prince Harry's privacy case against Associated Newspapers, the publisher of the Daily Mail newspaper, on Tuesday.
Harry and six others - including singer Elton John - had brought the case against the publisher, with each of them alleging that they had been the victims of unlawful information gathering for articles.
They accused Associated, which has denied any wrongdoing, of obtaining private and confidential information through techniques such as phone hacking and the use of private investigators.
In a written judgement published on Tuesday, Mr Justice Nicklin said the claimants had "failed to prove their pleaded allegations" and that the court could not simply infer that information had been unlawfully obtained if there was still a way it could have been sourced legally.
"Suspicion, even where understandable, was not enough. The Claimants had to prove that the information complained of had been obtained unlawfully," the judgement said. "The Court rejected the argument that, simply because information was private, and because Associated could not positively explain how it had been sourced, the relevant article must have been unlawfully sourced".
Nicklin said Associated journalists had also provided "lawful explanations for the sourcing of the disputed articles and incidents". He also dismissed claims that three senior Associated executives had lied in their evidence given to the 2011 to 2012 Leveson Inquiry into the culture, practices and ethics of the British press.
In a statement, an Associated Newspapers spokesperson called it an "overwhelming victory for the Daily Mail and its journalists" and a "magnificent vindication of the paper's journalism.
They also said that allegations of bugs placed in people’s cars and homes, phone tapping, and bank accounts being illicitly accessed were "lurid” and “preposterous” and that "no credible evidence was ever presented".
The court battle cost Associated more than £50 million in legal costs, which it will be seeking to recover, the spokesperson added.
Prince Harry has reportedly since described the ruling as "totally unwarranted" and a "whitewash".
"It is a complete and obvious whitewash, but sadly not altogether unexpected," Harry said in a joint statement with Doreen Lawrence, one of the other claimants in the case.
