'The USA is on the wrong side of history on this fundamental human rights issue. Governor Ryan has shown that change is possible and that principled human rights leadership is crucial,' the organisation added.

'Such leadership has been sadly lacking over the past quarter of a century of judicial killing in the USA,' Amnesty International said. 'Governor Ryan has shown that there is an alternative to the empty 'tough-on-crime' politics of the death penalty.'

The Governor, who has gone from death penalty advocate to one of its more outspoken critics, announced his commutation decision three years after he imposed a moratorium on executions in Illinois because of its 'shameful record' of wrongful convictions in capital cases. However, his blanket commutation decision made clear that the system was 'haunted' not only by error in determining guilt but also 'error in determining who among the guilty deserves to die'.

'Illinois is not alone in sending the innocent to death row,' Amnesty International continued, noting that more than 100 people have been released from the country's death rows after evidence of their innocence emerged. 'It is also not alone in overseeing a capital justice system where arbitrariness is a defining characteristic. Other politicians should take the lead from Governor Ryan, and begin to guide their jurisdictions away from this outdated punishment.'

Race, economic status and location of the crime all play a role in who is sentenced to death in the USA. A study released last week on capital sentencing in Maryland is just the latest to show a system plagued by racial and geographic bias. Eighty per cent of the more than 800 people executed in the USA since 1977 were convicted of crimes involving white victims. Yet blacks and whites are the victims of murder in almost equal numbers in the USA.

Advocates of this punishment argue that the system is winnowing out the 'worst of the worst'. However, time and time again cases come through the system which indicate the inevitability of human inconsistency and error.

'The death penalty in the USA has often been promoted as a route to emotional closure for the relatives of murder victims,' Amnesty International added. 'We join Governor Ryan in hoping that the US authorities can provide more than the hope of revenge to those who suffer the appalling trauma of losing a loved one to murder.'

'More than 100 countries have turned their backs on judicial killing,' Amnesty International said. 'This inexorable progress towards worldwide abolition reflects the growing realization that the death penalty is a punishment that is too flawed to fix.'