While the 40-year-old Australian was stuck in London traffic en route to the hearing, a courtroom packed with global media heard from Lord Phillips on Wednesday as he recounted the findings of a seven-member judicial panel.
For more than 18 months, Queensland-born Assange has been fighting a Swedish Public Prosecutor request that he be extradited to Stockholm for questioning over allegations of sexual assault against two women in August 2010.
Lawyers for Assange argued that the prosecutor was not a judicial authority, the title necessary to order an extradition.
Five justices at the UK Supreme Court disagreed with Assange, while two decided in his favour.
“The majority has concluded that the Swedish Public Prosecutor was a judicial authority … it follows that the request for Mr Assange‘s extradition has been lawfully made and his appeal against extradition is dismissed,” Lord Phillips said.
Assange‘s barrister, Dinah Rose, QC, pounced on the judgment, suggesting that the majority of justices based their decision on an interpretation of the Vienna Convention on the Law of Treaties, a point of law which had not been argued during the appeal hearing.
Subsequently, Ms Rose was granted 14 days to submit an application to the court which could lead to the appeal being reopened.
“The minority of judges considered that the words ‘judicial authority’ mean what they say: a court and a law,” Assange‘s solicitor Gareth Peirce told reporters outside court after the judgment.
“Lady Hale in her dissenting judgment considered that the basis on which the majority decided was putting the cart before the horse: that you cannot say that practice determines what the law means.”
Ms Peirce said the matter must be given further consideration by the court.
“We will be informing the Supreme Court that the basis on which the majority decided the Vienna Convention point, the practice, trumping the law, was not argued before the court at all and we therefore didn’t have an opportunity to argue it and that in itself would be a breach of … a fair hearing,” she said.
Assange has previously indicated that if his Supreme Court appeal was unsuccessful he would consider taking his case to the European Court of Human Rights.
Human rights lawyer Geoffrey Robertson, QC, said the British Supreme Court decision was “inevitable” but not unanimous.
“There are technical possibilities and of course the main issue is the European Court of Human Rights because that is the final court in Europe, and certainly he has a reasonable prospect there, but it is unlikely that they would halt the extradition,” he told the ABC.
Prime Minister Julia Gillard said Australia would provide consular services to Assange.