Tackling unjust sentences

It's 9am on a Sunday morning and Danny Glover - known to millions as the endearingly beleaguered Murtaugh in the Lethal Weapon franchise - is holding forth on why the death penalty has such a hold on the imagination of the American people.

'It's a policy that has always been presented as a perfect solution,' he says. 'People believe in it because it taps directly into their fear. In that respect, it holds public opinion hostage. But it's not perfect and innocent people have died because of it.'

Glover is just one of the many celebrities, from Tim Robbins and Susan Sarandon to Alanis Morissette, who have chosen to appear in The Exonerated, which opens in London this week at the Riverside Studios (Glover joins the cast next month). The play's starry endorsement during its 18-month off-Broadway run helped make it into a theatrical cause celebre.

Hollywood actors are often mocked for jumping on to the liberal bandwagon but for Glover, the play offers a genuine - and all too rare - opportunity for him to, as he puts it, 'share my relationship with the world'.

Glover has been petitioning against the death penalty since he was a teenager: he was among those who lobbied George Bush as state governor of Texas in 1999 to retry Gary Graham, sentenced to death for murder on evidence many believed to be unsafe.

The Exonerated deals with the story of six people wrongly convicted and sentenced to die by a system that has now notched up 1,000 executions since 1976.

Using the now familiar technique of direct testimony, compiled by Jessica Blank and Erik Jensen, it includes such travesties of justice as the case of Kerry Max Cook, who spent two decades on death row - the longest period endured by a man subsequently set free.

Sunny Jacobs is another of those six. In 1976, she was sentenced to death for shooting a police officer on the basis of false testimony by her co-accused, Walter Rhodes.

During her confinement her boyfriend Jesse Tafero, convicted of the same crime as Sunny, was executed. Sunny's sentence was commuted to life imprisonment in 1981 and she was finally released in 1992. She has always maintained her innocence.

'The play has given us all a voice,' says Jacobs, who now lives in Ireland. 'Otherwise our experiences would take up 15mins on the news and then be forgotten.'

There's a danger in thinking that The Exonerated preaches to the converted - no one in their right mind could think that executing innocent people was right. Yet the power of the play to change minds can be measured in real terms.

In 2003, governor George Ryan commuted all death row sentences in Illinois after receiving a petition organised by actors who had appeared in the play; he also requested to see a performance.