WIKILEAKS FOUNDER Julian Assange took his extradition battle to the UK’s supreme court today, arguing that sending him to Sweden would violate a fundamental legal principle.

The two-day hearing will be Assange’s last chance to persuade British judges to quash efforts to send him to Scandinavia, where he is wanted on sex crime allegations.

The case hinges on a single technical point: whether Sweden’s public prosecutor can properly issue a warrant for Assange’s arrest.

In the UK, generally only judges can issue arrest warrants and UK courts only honour warrants issued by what they describe as judicial authorities.

However, lawyers for Sweden argue that in their country – as in other European nations – prosecutors play a judicial or semi-judicial role.

Assange’s lawyer, Dinah Rose, rejected that argument Wednesday, telling the seven justices gathered in the UK’s highest court that a prosecutor “does not, and indeed cannot as a matter of principle, exercise judicial authority.”

She said that was not just a parochial British view, but rather a “fundamental principle” which stretches back 1,500 years to the Codex Justinius, the famous Byzantine legal code.

“No one may be a judge in their own case,” Rose said.

Read: Assange granted leave to appeal Swedish extradition>

Read: Assange wins right to further appeal extradition to Sweden>