Ernest Ray Willis set a fire that killed two women in Pecos County. So said Texas prosecutors who obtained a conviction in 1987 and sent Mr. Willis to death row. But it wasn't true.

Seventeen years later, a federal judge overturned the conviction, finding that prosecutors had drugged Mr. Willis with powerful anti-psychotic medication during his trial and then used his glazed appearance to characterize him as "cold-hearted." They also suppressed evidence and introduced neither physical proof nor eyewitnesses in the trial – and his court-appointed lawyers mounted a lousy defense. Besides, another death-row inmate confessed to the killings.

The state dropped all charges. Ernest Ray Willis emerged from prison a pauper. But he was lucky: He had his life. Not so Carlos De Luna, who was executed in 1989 for the stabbing death of a single mother who worked at a gas station. For years, another man with a history of violent crimes bragged that he had committed the crime. The case against Mr. De Luna, in many eyes, does not stand up to closer examination.

There are signs he was innocent. We don't know for sure, but we do know that if the state made a mistake, nothing can rectify it.

And that uncomfortable truth has led this editorial board to re-examine its century-old stance on the death penalty. This board has lost confidence that the state of Texas can guarantee that every inmate it executes is truly guilty of murder. We do not believe that any legal system devised by inherently flawed human beings can determine with moral certainty the guilt of every defendant convicted of murder.

That is why we believe the state of Texas should abandon the death penalty – because we cannot reconcile the fact that it is both imperfect and irreversible.

Flaws in the capital criminal justice system have troubled us for some timeyears. We have editorialized in favor of clearer instructions to juries, better counsel for defendants, the overhaul of forensic labs and restrictions on the execution of certain classes of defendant. We have urged lawmakers to at least put in place a moratorium, as other states have, to closely examine the system.

And yet, despite tightening judicial restrictions and growing concern, the exonerations keep coming, and the doubts keep piling up without any reaction from Austin.

From our vantage point in Dallas County, the possibility of tragic, fatal error in the death chamber appears undeniable. We have seen a parade of 13 men walk out of the prison system after years – even decades – of imprisonment for crimes they didn't commit. Though not death penalty cases, these examples – including an exoneration just last week – reveal how shaky investigative techniques and reliance on eyewitnesses can derail the lives of the innocent.

The Tulia and the fake-drug scandals have also eroded public confidence in the justice system. These travesties illustrate how greed and bigotry can poison the process.

It's hard to believe that such pervasive human failings have never resulted in the death of an innocent man.

In 2001, Supreme Court Justice Sandra Day O'Connor said, "If statistics are any indication, the system may well be allowing some innocent defendants to be executed."

Some death penalty supporters acknowledge that innocents may have been and may yet be executed, but they argue that serving the greater good is worth risking that unfortunate outcome. Supreme Court Justice Antonin Scalia argues that the Byzantine appeals process effectively sifts innocent convicts from the great mass of guilty, and killing the small number who fall through is a risk he's willing to live with. According to polls, most Texans are, too. But this editorial board is not.

Justice Scalia calls these innocents "an insignificant minimum." But that minimum is not insignificant to the unjustly convicted death-row inmate. It is not insignificant to his or her family. This marks a transgression against the Western moral tradition, which establishes both the value of the individual and the wrongness of making an innocent suffer for the supposed good of the whole. Shedding innocent blood has been a scandal since Cain slew Abel – a crime for which, the Bible says, God spared the murderer, who remained under harsh judgment.

This newspaper's death penalty position is based not on sympathy for vile murderers – who, most agree, deserve to die for their crimes – but rather in the conviction that not even the just dispatch of 10, 100, or 1,000 of these wretches can remove the stain of innocent blood from our common moral fabric.

This is especially true given that our society can be adequately guarded from killers using bloodless means. In 2005, the Legislature gave juries the option of sentencing killers to life without parole.

The state holds in its hands the power of life and death. It is an awesome power, one that citizens of a democracy must approach in fear and trembling, and in full knowledge that the state's justice system, like everything humanity touches, is fated to fall short of perfection. If we are doomed to err in matters of life and death, it is far better to err on the side of caution. It is far better to err on the side of life. The state cannot impose death – an irrevocable sentence – with absolute certainty in all cases. Therefore the state should not impose it at all.