Almost every American president or aspiring president in recent memory has had one: a dubious death-penalty case that underscores a line dividing the United States and Europe. Barack Obama's is that of Troy Davis, who sat on Georgia's death row for more than 20 years, convicted of murdering an off-duty policeman, and died by lethal injection yesterday morning.
Davis was unusual in protesting his innocence to the bitter end, and in the strength of support his case drew beyond the usual narrow circle of campaigners. No DNA or firearms evidence was ever presented to justify his conviction, and almost all the witnesses who had testified against him changed their story along the way. These were all reasons why the execution was delayed for five hours while the Supreme Court considered a last-minute plea for clemency.
In other ways, though, Davis's case was not unique – at least not in the challenge it presented to otherwise liberal US politicians. Ever since 1988, when Willie Horton effectively ended the presidential chances of Michael Dukakis by committing a murder while on weekend parole, presidents and presidential candidates have run scared of opposing the death penalty.
Dukakis was found wanting on two counts. First, because it was his parole policy, when governor of Massachusetts, that had freed Horton to kill. But second – and still more memorably – because, when asked during a presidential debate, whether he would still oppose the death penalty even if his wife were raped and murdered, he gave the high-minded liberal answer: there were "better and more effective ways to deal with violent crime". Dukakis was thus branded both soft on crime and severely lacking in the chivalry department.
Bill Clinton travelled a similar course. A foe of capital punishment in his youth, he believed he lost the governership of Arkansas after one term because of insufficient zeal for the death penalty. A murderer he had freed went on to kill again, and his Republican opponent did not let him forget it. Clinton subsequently won back the governorship, but he never forgot that lesson – or the spectacle of the defeated Dukakis.
He showed how much he had taken both to heart in 1992 when, as the Democratic presidential candidate, he flew home to Arkansas to watch the execution of Rickey Ray Rector. The guilt of Rector, convicted of killing a police officer, was not in doubt, but his execution was controversial because he was brain-damaged; he had shot himself in the head after the killing.
Even that arch-Republican proponent of capital punishment, George W Bush, had a death-row moment. As governor of Texas and aspiring president, he ran into trouble over the case of Karla Faye Tucker. The difficulty here was not Tucker's culpability (though she had pleaded diminished responsibility to the axe-murder as a result of drugs), but the abundant evidence that she had been "born again" and wanted to dedicate her life to good works, even if it had to be within prison walls. Her gender also played a part: there is more than a streak of old-fashioned chivalry in American conservatism.
Bush, who made much of how he, too, had been "born again", had to choose between redemption and retribution. Politically, of course, for a southern governor and would-be president, it was no contest. Tucker went to her death, the first woman to be executed in Texas for 135 years, despite pleas from former President Jimmy Carter, the Vatican and many, many more.
All of which helps explain why Obama, for all his liberal credentials – which include the recent repeal of Clinton's "Don't ask, don't tell" policy on homosexuals in the military – declined to intercede on Troy Davis's behalf. Few Americans would have been shocked, or even surprised, by this. Two thirds of the way through your first term is no time to seem to wobble on the death penalty if, as Obama appears to do, you intend to seek re-election.
This may not be the America, or even the American South, of To Kill a Mockingbird. But some of those instincts have survived the civil rights movement, the appointment of a black Supreme Court justice (Clarence Thomas), and even the election of a black president. Every poll will show that more Americans want vengeance, demand a life for a life and – though much more quietly these days – harbour suspicion of the black man – than naturally laud the quality of mercy. At any one time, black Americans are disproportionately represented on death row.
Not that the quest for retribution is unique to the US. Left to themselves, many Europeans – Britons included – would vote by quite a margin to restore the death penalty. If there is one policy that divides broad public sentiment from elite opinion across Europe it is capital punishment. The difference between the US and here is that "the people" more often get their way.
Some would say this reflects a residual frontier mentality, where brute force lies closer to the surface than it does in most countries of Europe. Others might argue that the judicial system in the United States remains more populist than it does in Europe. With elected police chiefs and judges at all levels confirmed by elected legislatures, these arbiters have a mandate and are in little doubt of what is expected of them.
It could also be observed that the average American worries less about killing an innocent individual than about letting a dangerous person go free. The assessment of risk and safety is different; the compass for "reasonable doubt" often seems to be set at a different place.
In fact, the US picture is not uniform. A few states have always opposed capital punishment; others have abolished or suspended it. Those both retaining and applying the death penalty are concentrated in the south, although it remains also at federal level. So, while deploring the continued use of the death penalty in the US, Europeans might more productively marvel that there are not more executions – there were 46 in 2010 – and consider how and why the use of the death penalty has fluctuated in recent years.
Between the mid-1960s and mid-1970s there was an effective moratorium, as issues of racial discrimination, inadequate legal representation and procedural inconsistencies came to the fore. There was a new spate of suspensions 10 years ago, when DNA evidence became accepted in court, and some past mistakes came to light. Now, though, DNA technology shifts the argument the other way. With more convictions upheld by DNA evidence, mistakes are less likely, or so death-penalty supporters would contend.
The harsh reality is that outsiders will not convince Americans to change their executing ways. Any shifts have come in response to proof of discriminatory treatment or miscarried justice. And this – as admirable organisations, such as Clive Stafford Smith's Reprieve, well know – is where the focus of campaigning should be. Even in the unlikely event that new evidence places Troy Davis's innocence beyond doubt, the principle of a life for a life will remain entrenched. It is something on which the two sides of the Atlantic will have to agree to differ.