This week’s protracted execution of Dennis McGuire at the Southern Ohio Correctional Facility outside of Lucasville has many wondering if lethal injection is a more humane way of death after all. Under the administration of an untested lethal drug combination, McGuire emitted disturbing sounds suggesting a painful, drawn-out suffocation.

The number of U.S. executions is declining, according to Death Penalty Information Center, as are the number of states that impose them. But questions about the justness of the death penalty are growing as death row inmates continue to be found innocent, racial disparities and questions of mental competency continue to surface and lethal injection is questioned as a humane death method.

Since the 1990s, Deborah W. Denno, professor of law at Fordham University School of Law, has been a leading opponent of death by electrocution, asserting that it violates the Eighth Amendment's prohibition again cruel and unusual punishment.

"There's substantial evidence that suggests electrocution results in a high risk of pain and prolonged suffering," Denno told the Sun-Sentinel. "Can people say that for an absolute certainty? No. You can't interview a dead person. But when the other side comes back and says there's no evidence of that, that these people die instantaneously, they're being dishonest."

The electric chair—or the "hot squat" as it is sometimes called—has largely been replaced by lethal injection in the U.S. because of the appearance that lethal injection is more humane. But lethal drugs are likely just as cruel says Denno, because of "grossly inadequate" protocols about which drugs are administered, how, by whom and in what quantities and the clandestine nature of lethal injections. In a 2007 Fordham Law Review article, Denno wrote that states need to "take their execution procedures out of hiding." She is also concerned about newer drugs increasingly used in lethal injections. "We don't know how these drugs are going to react because they've never been used to kill someone," she told Mother Jones.

The electric chair has a ghoulish history, from its invention by employees of Thomas Edison , to grisly mishaps like Willie Francis who failed to die in 1946 and had to take the "long walk" twice, to Pedro Medina whose face mask burst into flames in 1997. Yet lethal injection, also called Carson's Cocktail after the Oklahoma pathologist who concocted the original formulation, is also prone to mishaps like the 2007 case in which guards failed to find a vein and sobbing inmate Romell Broom was asked to find his own vein. (The "self-execution" still failed and Broom will also made the long walk twice.)

What happened to Broom is to be expected. Even though it takes a skilled nurse or hemophylist to insert catheters snugly, so the fluid doesn't leak or the catheters come loose by the writhing of a distraught prisoner, this complex medical responsibility is assigned to prison guards. After the guards have marched the prisoner to the death room and strapped him to the gurney, the search for big veins to insert the catheters starts. Guards have been known to fumble for hours, sometimes cutting open the prisoner's veins with a knife or scalpel, before the warden calls a halt to the proceedings.

The Carson Cocktail consists of three drugs: a short-acting barbiturate to knock the condemned person out (originally thiopental); a neuromuscular blocking agent to paralyze the skeletal muscles, including the breathing muscles (pancuronium bromide); and an agent that stops the heart (potassium chloride).

Right after the thiopental infusion, pancuronium bromide is administered, a curare type agent that paralyzes the skeletal and breathing muscles. Theoretically, the condemned is now soundly asleep and prepared to die, thanks to the upcoming infusion of potassium chloride, a drug that stops the heart. Theoretically. If the dose of thiopental is inadequate, the execution will go wrong in a horrific way: potassium chloride causes agonizing pain, yet there is no way for the condemned to convey this because all his muscles, even speech, are paralyzed.

It is not a great way to die. If anything, U.S. lethal injections are becoming worse as Thursday's execution of McQuire demonstrated. Since the manufacturer of sodium thiopental ceased production under pressure from the government in Italy, where its plant is based, other European manufacturers also refuse to provide thiopental because of a European Union statute prohibiting the export of any product that might be used in capital punishment.

Last fall, convicted murderer William Happ was executed in Florida using the sedative midazolam to replace thiopental. Midazolam is a drug "that causes memory loss and relaxation, but not necessarily unconsciousness," according to the Week . It took 14 minutes to kill Happ rather than the planned seven and "his head shook throughout, and his eyes remained open until the 10th minute." Ohio used midazolam along with the painkiller hydromorphone when it executed Dennis McGuire on January 16. Commensurate with Denno's concerns, it was an untested lethal injection: "No state has put a prisoner to death with those drugs in any fashion," said the AP.

Other states have pursued the animal anesthetic pentobarbital to replace thiopental but it is only available through compounding pharmacies and not always legal to use, says the Week. Texas' Department of Criminal Justice "allegedly submitted a falsified prescription to one compounding company, Pharmacy Innovations, ostensibly for patient 'James Jones'—actually the warden of the Huntsville Unit, which houses the execution chamber," says the Week. "Other states have bought lethal injection drugs with petty cash or individual employees' credit cards."

National Public Radio reports that the state of Missouri has also sought to replace thiopental with pentobarbital from a compounding pharmacy and " fought hard to keep the identity of the supplier a secret, restricting public oversight, and making it difficult to know if the execution method is both legal and ethical."

Of course, a U.S. execution is already secretive. After the prisoner is strapped down and the needles inserted, the drape is closed and the audience only sees the supine prisoner with long tubes running from his arm to a hole in the wall. The warden and chief executioner who "work" the chemical from the other side of the wall are never seen. Sometimes there are not even witnesses.

But now secrecy extends to "Individuals who prescribe, compound, prepare, or otherwise supply the chemicals for use in the lethal injection procedure,” charges National Public Radio . "It’s just a shroud of secrecy to try to prevent criticism and skepticism from the public," agrees American Civil Liberties Union of Missouri legal director Tony Rothert. “I think the First Amendment gives the public the right to know who the execution team is, and to question whether or not they’re qualified."