Audio Transcript:

KATY CLARK: I'm Katy Clark, and this is The World. Gary McKinnon describes himself as a �bumbling computer nerd.� The US government thinks otherwise. Federal prosecutors accuse McKinnon, a British citizen, of the �biggest military hack of all time.� US authorities have been trying to get McKinnon extradited from Britain for three years. McKinnon, his family, and his lawyers have been fighting that extradition. But today, a ruling by Britain's high court may leave McKinnon without further legal recourse in his home country. The World's Clark Boyd reports.

CLARK BOYD: The charges leveled at Gary McKinnon are substantial. The US indictment alleges that just after the 9/11 terrorist attacks in 2001, McKinnon � using his online name �Solo�, began hacking into nearly 100 US Army, Navy, Air Force, and even NASA computers. McKinnon stands accused of causing a US Army network of more than 2,000 computers in the Washington, DC area to be offline for 24 hours. His hacking allegedly caused hundreds of thousands of dollars in damage and hampered systems critical to American security. He could face more than 50 years in prison and millions of dollars in fines if convicted here. So, is McKinnon some sort of super-hacker? Not really. This week, McKinnon repeated the same thing that he has for years now � that he simply found US government computers, some containing very sensitive information � that were not even password protected.

GARY MCKINNON: Unauthorized access is all I'm guilty of � not willful damage. I wasn't vandalistic or malicious.

BOYD: He maintains, as he always has, that all he was doing was looking for evidence of the existence of unidentified flying objects and pollution-free energy sources. And he continues to dispute the US government's estimates of the damage he caused.

MCKINNON: That's the key thing. That's what's made this thing a huge case now, the accusations of widespread damage. But they had to accuse me of damage, otherwise it wouldn't have been an extraditable offense.

BOYD: Extradition � that's been the focus of the three-year legal battle between McKinnon and the US government. McKinnon and his lawyers argue that he should be tried in the United Kingdom under the Computer Misuse Act. After all, they argue, he did the hacking � sometimes in his pajamas � from his apartment in London. McKinnon has even said he will plead guilty in a British court and serve his time there without a fuss. Julian Knowles is a London-based extradition lawyer not involved in the case. He says US prosecutors see things differently.

JULIAN KNOWLES: The effects of what Gary McKinnon were alleged to have done were felt in the United States, and, say the United States, were very serious. For that reason, they claim the right to put him on trial and have initiated the extradition process, because the effects of what he did were felt in the U.S.

BOYD: And so, for three years now, US authorities have been trying to get McKinnon out of Britain to stand trial in a US federal court. Last year, McKinnon was diagnosed with Asperger's Syndrome, a form of autism. So in the latest appeal to Britain's High Court, his lawyers argued that standing trial in the United States might cause him to become psychotic or suicidal. But High Court justices dismissed those claims and maintained that the United States is the proper venue for McKinnon's trial. McKinnon's case has become something of a cause celebre in Britain. Musicians David Gilmour, Crissy Hynde and Bob Geldof made a video in support of McKinnon. Even Britain's internet security professionals are largely behind Gary McKinnon. The internet security firm Sophos surveyed IT professionals � the people normally tasked with protecting computer systems � and found a majority say McKinnon shouldn't face extradition. Graham Clueley is senior technology consultant at Sophos.

GRAHAM CLUELEY: Most of the hackers and attacks we see these days are financially motivated. McKinnon � the worst you can say about him is that he was a UFO conspiracy nut. So he cuts a sad and pathetic image of himself, and people don't see him as much of a threat. And many people actually think maybe the US was slightly to blame, because in the months following 9/11, they weren't using proper passwords to secure some of their computers.

BOYD: McKinnon's lawyers have 28 days to review the High Court's decision. They say they'll try to appeal in whatever venue they can, even the US Supreme Court. And they've sent a letter signed by some 40 British politicians asking President Obama to, quote, �step in and bring this shameful episode to an end.� For The World, this is Clark Boyd.

CLARK: Clark covers all the latest in global tech news every week on his Technology Podcast. Just visit theworld.o-r-g/podcasts to subscribe.