WikiLeaks founder Julian Assange will ask Britain’s Supreme Court on Wednesday to quash a decision to extradite him to Sweden.
Swedish prosecutors want Assange to answer allegations that he sexually assaulted two women who once worked for his website.
The case comes after a lower court rejected an appeal to block his extradition.
The claims came to light at a time when WikiLeaks faced intense scrutiny from Washington for publishing secret US diplomatic cables.
Assange says the charges are politically motivated and fears Sweden plans to extradite him to the United States.
He may take his case to the European Court of Human Rights if this appeal fails.
The 40-year-old faces other legal woes: his former lawyers are suing him in a separate case over unpaid fees.