Two High Court judges certified the WikiLeaks founder had raised a question on extradition law “of general public importance”, paving the way for him to go to the Supreme Court.
Sir John Thomas, sitting in London with Mr Justice Ouseley, refused the 40-year-old Australian direct permission to appeal after Sir John described Assange’s chances of winning as “extraordinarily slim”.
But the judges gave him 14 days to ask the Supreme Court justices themselves to give a final ruling.
If the Supreme Court refuses to hear his arguments, or he loses a full appeal, his remaining option will be to take his case to the European Court of Human Rights in Strasbourg.
Assange has fought a series of legal battles, arguing that it would be “unfair and unlawful” to order his extradition. The Swedish authorities want him to answer accusations of raping one woman and “sexually molesting and coercing” another in Stockholm in August last year. He denies the allegations and says they are politically motivated.
His WikiLeaks website has published a mass of leaked diplomatic cables and other documents, embarrassing several governments and international businesses.
Recently, the High Court upheld a ruling by District Judge Howard Riddle at Belmarsh Magistrates’ Court that the computer expert should be extradited.
Mark Summers, appearing for Assange, said his client was detained under a European Arrest Warrant (EAW) issued by a Swedish public prosecutor. Seeking permission to appeal against the High Court decision, Mr Summers said he wanted to ask the Supreme Court to rule that public prosecutors were not “judicial authorities” entitled to issue warrants under extradition law and, therefore, the Assange warrant was invalid.
He told the judges a “disproportionately high” number of EAWs found to have been unjust or oppressive emanated from public prosecutors who “should not, in any circumstances, be permitted to issue EAWs”.
Sir John told Mr Summers the court’s view was that it had “very little doubt that, as a matter of law, the prosecutor was within the scheme” for issuing warrants, and Assange’s chances of success in the Supreme Court were “extraordinarily slim”. But at the end of the hearing the judge said the court felt “constrained” to certify that the case raised at least one question of general public importance.
Later Assange was cheered as he left the Royal Courts of Justice in London.
Assange said: “This afternoon the parliament of the UK is considering in depth the matters that arise from various extradition cases in the UK, including my own.
“I think that is the correct decision, and I am thankful. The struggle for justice for me and others continues.”