The Swedish prosecutor who issued an arrest warrant for WikiLeaks founder Julian Assange is not a neutral party, his lawyer told a British court Wednesday. Dinah Rose asked the U.K. Supreme Court to quash Assange\'s extradition order, The Guardian reported. The appeal is Assange\'s last hope of avoiding extradition to Sweden to face two women\'s charges that he sexually assaulted them. Rose quoted the Code of Justinian that \"no one should be judge in their own cause.\" She said European agreements on criminal law and extradition are consistent with that principle while the Swedish public prosecutor is, in effect, a party to the case. \"The words \'judicial authority\' can only be understood as meaning an independent judge or a person executing equivalent power,\" Rose said. The courtroom was packed with Assange\'s supporters. The hearing is expected to run through Thursday. The seven justices are likely to reserve their decision. Assange has not been formally charged with a crime in Sweden yet. Legal experts said the courts tend to give other countries\' legal systems the benefit of the doubt, which means Assange has an uphill fight. \"I don\'t think he\'ll succeed,\" Peter Caldwell, an extradition lawyer, told The Guardian. Assange\'s supporters say they fear extradition to Sweden is a precursor to an extradition to the United States, which is conducting an investigation into the leak of hundreds of thousands of diplomatic cables and documents on the wars in Iraq and Afghanistan to the whistle-blowing Web site. An Army private faces a court-martial in the matter. Euronews.net reported Assange may appeal to the European Court of Human Rights if the U.K. Supreme Court rules against him.