Julian Assange’s lawyers will begin their final UK legal challenge on Tuesday to stop the WikiLeaks founder from being sent to the US to face spying charges. The 52-year-old has been fighting extradition for more than a decade, including seven years in self-exile in the Ecuadorian Embassy in London and the last five years in a high-security prison.

Assange’s attorneys will ask two High Court judges to grant a new appeal hearing, his last legal roll of the dice in Britain. If the judges rule against Assange, he can ask the European Court of Human Rights to block his extradition—though supporters worry he could be put on a plane to the US before that happens.