Gary McKinnon suffers from Asperger's Syndrome
Campaigners are to hold a protest outside the US Embassy in London against the extradition of computer hacker Gary McKinnon to America.
His supporters argue that when a crime occurs in the UK a British court should be able to refuse extradition.
The US wants to try Mr McKinnon, 43, for what it calls the biggest military computer hack ever in 2001/02. He maintains he was seeking UFO evidence.
The Asperger's Syndrome sufferer lost a court bid to avoid extradition.
Liberty say that British courts should be allowed to veto extradition "if it's in the interests of justice to do so".
The group added: "Liberty also holds that the requesting country should have to make out the case for extradition in a British court before the request is granted."
Glasgow-born Mr McKinnon admits hacking by accessing 97 government computers belonging to organisations such as the US Navy and Nasa, but denies it was malicious.
He also denies the allegation he caused damage costing $800,000 (£487,000).
He has always insisted he was looking for classified documents on UFOs, which he believed the US authorities had suppressed.