One drug, pancuronium bromide, paralyzes the inmate. This "eliminates convulsions and thus provides a dignified death to the inmate and witnesses to the execution," Kentucky's attorneys argue in legal briefs. Put another way, the drug-induced paralysis "protects the witnesses from watching an unpleasant death, but also masks the ability ... to know whether the inmate is experiencing searing pain or conscious suffocation," according to a brief filed by Berkeley's Death Penalty Clinic and its associate director, Ty Alper.

Another drug, sodium thiopental, is an anesthetic now rarely used in hospitals. A third drug, potassium chloride, stops the heart. Taken together, the drugs ensure that death-row inmates will die in a "relatively humane manner," Kentucky's attorneys argue.

Administered improperly, inmates' attorneys respond, the drug combination can become tantamount to torture.

In December 2006, for instance, Florida murderer Angel Diaz took 34 minutes to die because of botched procedures. A subsequent state investigation concluded that it was "impossible" to know whether Diaz was in pain, even though 12-inch chemical burns were later found on both of his arms. In January 1992, in an execution overseen by then-presidential candidate Bill Clinton, Arkansas witnesses heard convicted murderer Ricky Rector moaning in apparent pain while a five-man execution team tried for 50 minutes to find a vein.

"Kentucky's haphazard and ill-considered lethal injection procedures exacerbate the risk that some condemned prisoners will suffer an excruciating death," Frankfort-based attorney David M. Barron argued in his legal brief for Baze and Bowling.

As a technique, lethal injection reflects the ongoing search for a clean-cut method for killing criminals. The guillotine, for example, was conceived as a humane replacement for the ax, the sword and more gruesome methods such as burning at the stake. Electrocution was "devised for reaching the end proposed as swiftly and painlessly as possible," Justice Oliver Wendell Holmes Jr. noted in 1901.

Officials later scrapped the electric chair following episodes such as the March 1997 electrocution of Florida murderer Pedro Medina, in which witnesses reported seeing smoke and flames shoot out of the helmet covering Medina's head.

—Supreme Court to weigh whether lethal injection is cruel

I have to wonder why it is so hard for such a scientifically and technologically advanced civilization as ours to find a way to kill people who aren't even fighting back, without causing flames to shoot out the head and chemical burns to fester and open on their arms and chopped off heads and broken necks and questions of torture and agony? Personally, I think we must want those people to suffer. If we didn't, why wouldn't we have just chosen a heroin overdose for all of them by now? Cheap, quick, easy, painless, dead. Doesn't that solve all the problems? [update: here, we could easily substitute "narcotic overdose" and i mean "Narcotic" as in the technical drug family, not the slang for "drug."]

It does unless you want them to suffer as they die, and you want them to be looking forward to a painful and horrible death in their last days. That to me, seems like a chosen form of torture in and of itself.