CHICAGO - A botched lethal injection in Oklahoma this week has renewed a debate on whether doctors should be banned from executions - or required to participate to make the process more humane.

Some of the nation's 32 death penalty states mandate doctor participation - including Oklahoma - but critics say that what happened there proves a doctor's presence can't guarantee the process will go smoothly.

"Physicians have an ethical and moral responsibility to remain as far from the execution chamber as possible," said Jonathan Weisbuch of Phoenix, a physician and death-penalty opponent. He calls what happened in Oklahoma torture. "How dare they experiment on a living human being," he said.

In Oklahoma on Tuesday, the execution team struggled to find a suitable vein for injecting the lethal drugs, and a vein collapse prevented the drugs from working properly. Clayton Lockett, a convicted murderer, writhed before the execution was called off. He died later of an apparent heart attack. According to witnesses and a letter from the state's prisons chief, a physician checked the IV line, checked to see whether Lockett was unconscious, and reported that not enough drugs had been given to kill him - all violations of the American Medical Association's ethics policy.

The AMA says it's unethical for doctors to be involved except in a peripheral way. That's one reason the number and identities of physicians who do participate are shrouded in secrecy. Ardis Dee Hoven, the AMA's president, issued a statement Friday regarding Lockett's execution.

"No matter how one feels about capital punishment, it is disquieting for physicians to act as agents of the state in the assisting, supervising, or contributing to a legally authorized execution," Hoven said. The AMA "is troubled by continuous refusal of states to acknowledge the ethical obligations of physicians that strictly prohibit involvement in capital punishment."

Weisbuch says the Oklahoma case underscores why an execution moratorium is needed. He plans to ask the AMA, at the group's policy-making meeting next month in Chicago, to lobby for a ban. Similar attempts have failed. But whether Lockett's execution, execution drug shortages, and concerns about their effectiveness will sway the AMA this time remain to be seen.

Richard Dieter, executive director of the Death Penalty Information Center, an advocacy group critical of how capital punishment is usually carried out, said doctors' participation in executions often pitted the medical profession against the judicial system. "Courts want assurances," he said, that condemned inmates won't suffer.

Yet, even if doctors don't feel bound by AMA policy, many strongly adhere to their oath to do no harm.

Dieter said that states' execution protocols often didn't specify what role doctors play and that they are updated, so it was difficult to quantify the number of doctors involved. Dieter said his organization hasn't kept tabs.

Here are some examples of current execution rules:

Texas says unspecified members of "the drug team" inject the drugs, and a physician enters the death chamber when the execution is over, "to examine the offender, pronounce the offender's death, and designate the official time of death."

North Carolina says a doctor will monitor the condemned inmate "and immediately notify the warden of any signs of undue pain or suffering."

Kentucky's mandate says, "No physician shall be involved in the conduct of an execution except to certify cause of death provided that the condemned is declared dead by another person."

Neil Farber, a University of California, San Diego, internist and educator, said surveys he did more than a decade ago found that almost 20 percent of doctors would be willing to perform lethal injections.

Farber said it was likely that Lockett's execution would change some minds.

"I sure hope so," he said. "I think it is something society needs to address."