Gary McKinnon, the UK citizen accused of breaking into and damaging Nasa's computers began his appeal against extradition to the US on Tuesday.
Edmund Lawson, QC, who is defending McKinnon, told a hearing at London's High Court that McKinnon faced up to 60 years' imprisonment if he was convicted in America, where he could be tried under its anti-terrorism legislation.
Lawson also revealed that McKinnon had been offered a deal by US authorities, under which he would receive a shorter sentence if he stopped fighting extradition. This offer had been rejected, and constituted an "improper approach" to McKinnon, Lawson claimed.
McKinnon is accused of illegally hacking into 97 US government computers in 2001 and 2002, causing $700,000 worth of damage. In an interview with ZDNet UK, McKinnon admitted accessing the computers as part of his search for evidence of extraterrestrial life, but denied deliberately doing any damage.
Back in May 2006, a British judge ruled that McKinnon should be extradited to the US to face these charges.
The appeal is continuing on Wednesday, and may run into Thursday. If he loses, McKinnon is expected to try and appeal to the European Court of Human Rights.