Glenn Mulcaire, one of the two men jailed after the original police investigation into the now-defunct Sunday newspaper News of the World, had argued that the information he intercepted was "intellectual property" and so he should be allowed to keep it secret.
But his appeal was unanimously dismissed by five judges at the Supreme Court on Wednesday morning, having previously been rejected by the High Court and Appeal Court.
It means he must divulge - to Nicola Phillips, an employee of the publicist Max Clifford - the identity of the person at the Murdoch-owned tabloid who told him to listen into other people's voicemail messages.
