When the United States abolishes the death penalty, some of its most ardent proponents ironically may be remembered for having made the most effective case for its demise. Texas Governor Rick Perry's obvious attempt to suppress the truth in the supposed arson case against Cameron Todd Willingham, executed in 2004 for a crime that probably didn’t occur, reveals the heinousness of capital punishment. That an innocent individual can be executed is disturbing. That the death penalty—which has claimed about 50 lives in the United States so far this year—is used for political purposes, while doing nothing to deter violent crime, is abhorrent.

Less than two hours before Willingham's execution, Perry received a report challenging the central evidence against him for the supposed arson that killed his three young daughters. But Perry permitted the execution anyway. Five years after Willingham’s execution, the state Forensic Science Commission was on the verge of reviewing new findings that made a compelling case for his innocence. But recently, just two days before the commission's review, Perry began replacing all four governor-appointees on the commission. He called his move purely routine.

Maybe so. One week before Thanksgiving, Texas executed Robert Lee Thompson after Perry rejected a rare recommendation from the state clemency board for the prisoner's life to be spared. In that case, the person who actually shot the victim is serving a life sentence.

Why is this routine in Texas? Facing a Republican primary in March, Perry’s actions have struck most observers as purely political.

After all, the death penalty does more to help politicians get elected than keep us safe. Most criminologists believe that it doesn’t deter murder. A recent Death Penalty Information Center study shows that police chiefs around the country rank the death penalty last among measures that help fight crime. Nevertheless, few politicians publicly oppose it. Additionally, the election of district attorneys and judges creates such a strong political motive to secure harsh sentences that investigations and prosecutions can be sullied by manipulating evidence.

Securing testimony from dubious sources to justify a theory of someone’s guilt is too easy. For example, the government relied on a jailhouse snitch (the most dubious of all such sources) in Willingham’s case and in numerous other cases where strong innocence claims have later emerged. That’s a factor in the Georgia case of Troy Davis, who has spent two decades on death row and now will have a court hear his claim of innocence, following a ruling from the Supreme Court.

The death penalty gives government godlike power that, given human fallibility, is incredibly dangerous. In Willingham’s case, arson investigators used techniques that have since been debunked as “junk science.” While witnesses initially reported seeing Willingham attempting to help his children out of his burning house, they seemed to change their story and remember less sympathetic things about him once investigators started to say they saw clear signs of arson.

Texas and other states should improve their use of fire science and the best technical tools available. But bias and ambition can always corrupt perceptions and conclusions. Justifiable outrage over senseless killings can color emotions in the search for truth. Even the most honorable and well-intentioned prosecutors and judges can succumb to intense political pressure. The results, predictably, are wrongful convictions or, as in the Willingham case, a wrongful execution.

Supreme Court Justice Antonin Scalia said in 2006 that he didn’t believe the United States had executed anyone who was innocent. If that had happened, Scalia said, “we would not have to hunt for it; the innocent’s name would be shouted from the rooftops.”

Willingham's name isn’t being shouted from rooftops, though it should be, along with the names of other innocent men who were executed like Carlos de Luna, Ruben Cantu, and Larry Griffin. Have we become so numb that the killing of innocent people is acceptable?

Had Willingham been sentenced to life in prison, he could be a free man today.

Instead we are left to ask, as former Texas Governor Mark White recently did: Why do we impose the death penalty, given the possibility that an innocent person will be executed?