ST. LOUIS (AP) -- A federal appeals court on Monday opened the way for Missouri to resume executing condemned inmates, ruling the state's lethal injection procedure is not cruel and unusual punishment.

The case filed on behalf of condemned killer Michael Taylor had effectively halted Missouri executions since early last year. A judge said he wanted to be sure that the three-drug injection method did not cause risk of pain and suffering.

"Mr. Taylor presents no argument that the penalty of death by lethal injection is grossly out of proportion to the severity of his crime," the ruling from a three-judge panel of the 8th U.S. Circuit Court of Appeals said.

The court ruled it found "no evidence to indicate that any of the last six inmates executed suffered any unnecessary pain that would rise to an Eighth Amendment violation or that any state actor was deliberately indifferent to the Constitution's requirement that no unnecessary pain be wantonly inflicted during the execution process."

Attorney General Jay Nixon said capital punishment in Missouri offers safeguards against inhumane treatment of the condemned. He said the decision "reopens the necessary legal avenue for the state of Missouri to move forward on this issue."

Ginger Anders, Taylor's attorney, said she would appeal but declined further comment.

But Margaret Phillips of the Eastern Missouri Coalition Against the Death Penalty said many questions remain unanswered and it would be unwise for the state to renew executions.

"The uncertainty of all of this is a good indication that Missouri needs a moratorium on the death penalty," she said.

The court's decision reversed a ruling by U.S. District Judge Fernando Gaitan Jr. ordering reforms to Missouri's lethal injection procedures. He wanted the state to involve a doctor specializing in anesthesia, but the state has been unable to find a doctor willing to participate.

Missouri is among nine states that have put executions on hold as it grapples with whether lethal injection is inhumane.

The debate centers on how three drugs are administered in succession. If the initial anesthetic does not take hold, a third drug that stops a condemned prisoner's heart can cause excruciating pain, it has been argued. But the inmate would not be able to communicate the pain because of a second drug that paralyzes him.

But the court, in its ruling, stated, "The protocol is designed to ensure a quick, indeed a painless, death, and thus there is no need for the continuing careful, watchful eye of an anesthesiologist or one trained in anesthesiology, whose responsibility in a hospital's surgery suite (as opposed to an execution chamber) is to ensure that the patient will wake up at the end of the procedure."

Taylor, convicted of killing 15-year-old Ann Harrison in Kansas City in 1989, was moments away from being executed in February 2006 when the execution was halted.

The debate over executions increased last year after it was learned that Missouri's doctor responsible for overseeing administration of the lethal chemicals, identified as surgeon Alan Doerhoff of Jefferson City, was dyslexic. Anders has called relying on the dyslexic doctor for the process a "set-up for disaster."

Doerhoff testified last year that he'd overseen Missouri's executions for years, and on occasion he altered the amount of anesthetic given to inmates.

Anders was not arguing that Taylor's life be spared, although his family is hanging on to that hope.

Harrison was waiting for a school bus in Kansas City when Taylor and another man kidnapped and killed her in 1989. Taylor pleaded guilty and said he was high on crack cocaine at the time.

The last execution in Missouri occurred on Oct. 26, 2005, when convicted killer Marlin Gray was put to death. He was the 67th man executed since Missouri renewed the death penalty in 1989.

Forty-seven inmates are currently on death row, including Taylor and his accomplice in the Harrison killing, Roderick Nunley.