When the Supreme Court invalidated death penalty laws in 1972, Justice Potter Stewart wrote that the administration of the ultimate punishment was so inconsistent and capricious that the chances of receiving it were like being hit by lightning. The next year, the court began upholding revised laws that addressed those objections.

More than a quarter-century later, 640 executions later, the death penalty is again under attack. The old issue of arbitrary application is back, joined now by new concerns that innocent defendants are being railroaded by sloppy defense attorneys, overzealous police and prosecutors and politically driven judges.

A new Columbia University study of the death penalty, the most comprehensive ever, looked at the 4,578 death sentences handed down between 1973 and 1995. It found that error at trial caused 68 percent of those sentences to be overturned on appeal. Upon retrial, 82 percent of those defendants received lesser sentences and 7 percent were acquited.

In other words, when the question is who deserves death and who is guilty, the answer coming out the courts is overwhelmingly wrong. Death penalty advocates point to this reversal rate as evidence that the appeals process works. This ignores the obvious need for an overhaul of the courts, it assumes that all errors are caught during appeals and comes at a time when Congress and state legislatures are in a mad rush to curtail the appeals process, the one part of the system that, more or less, seems to work.

The situation was so bad in Illinois that three months ago Gov. George Ryan ordered a moritorium on executions. Here’s how bad: 13 men on death row had been cleared — found absolutely innocent — by new evidence. In the case that proved the final straw for that Republican governor, a man just 48 hours away from lethal injection was proved innocent not by a properly functioning appeals process but by evidence uncovered by Northwestern University journalism students.

But the focus of attention now is Texas, in part because its governor is running for president, but mostly because Texas is the most execution-happy of states — 218 since it reinstated the death penalty in 1982, 131 since George W. Bush became governor in 1995.

Gov. Bush has long defended his state’s death-penalty record, portraying its criminal justice system as a finely tuned machine that never fails. That makes his recent decision to allow a review of DNA evidence in a rape/murder case, the first time he has stepped in, a welcome admission that sometimes even finely tuned machines need checkups.

Now Gov. Bush must take the next step and order an overhaul. One death-row inmate has been denied a review because the state contends that the mere fact his court-appointed attorney slept through much of his trial does not necessarily mean he was inadequately represented. Another is scheduled to die next week, despite clear and mounting evidence that his identification by a lone eyewitness was rigged. At least nine men — Hispanics and blacks — ended up on death row after a psychologist engaged as an expert witness by the state told juries those particular defendants were likely to remain threats to society because of their race. Justice Potter’s lightning analogy remains true. In Texas it appears certain individuals are being sent out into the thunderstorm with lightning rods.

The present debate on the death penalty is not about whether execution is justice, it’s about whether justice is being executed. It remains true, as death penalty advocates assert, that an executed killer will never kill again. It also remains true that an innocent person executed remains forever innocent.