Britain deals blow to U.S. extradition treaty LONDON - The British government on Tuesday, seeking to roll back its controversial treaty allowing expedited extraditions to the United States, blocked the handover of an autistic computer wiz who hacked U.S. military databases and moved to enact legislation that could complicate future attempts by American prosecutors to pursue alleged criminals in Britain. The moves could ignite tensions in an otherwise close transatlantic relationship, and finds the Conservative-led British government responding to critics who have long argued against a "one-sided" 2003 treaty designed to make it easier for the United States to pursue terror suspects and other offenders on British soil. The changes could allow British courts to determine whether suspects should instead face trial here, effectively blocking extraditions to the United States in some cases. Theresa May, Britain's top authority on domestic affairs, also further outlined a sweeping move first announced Monday that would withdraw London from a series of European Union justice and policing measures. Tuesday's move pivoted around the decade-old case of Gary McKinnon, 46, who is described by U.S. authorities as having committed "the biggest military computer hack of all time." May issued an unprecedented ruling blocking McKinnon's extradition on humanitarian grounds. McKinnon, who has Asperger's Syndrome, was deemed by two psychiatrists, brought in by May to assess his mental health, as being at high risk of committing suicide if sent to the United States, where he faces up to 60 years in jail. May told the House of Commons on Tuesday that McKinnon was accused of "serious crimes," but she said he also was "seriously ill" and that the sole issue at stake was whether or not the extradition would "breach his human rights." "A decision to extradite would be incompatible with Mr. McKinnon's human rights," May said. But May also proposed a wider shake-up to Britain's 2003 extradition treaty with the United States, following widespread concerns here that it's too easy for British citizens to be sent to the United States for trial, and that a document critics say was initially intended for terror suspects only is being used far more broadly by U.S. prosecutors. In 2011, an independent review led by retired judge Scott Baker concluded that the U.S. - U.K. treaty did not operate in an "unbalanced" manner. But legal analysts here said sentiment that the treaty was lopsided prevails, in part, because U.S. prosecutors are more aggressive than their European counterparts in pursuing suspects outside of their territory. The new measures outlined by May would see an unactivated provision of the treaty come into force if approved by both houses of the British parliament that would make it easier for alleged offenders to be tried in Britain if the alleged crime happened here. The changes would mean a British judge would be able to decide whether a suspect should be tried in the U.K., or extradited to the U.S. to face trial.