Ohio Attorney General Thomas Madden believes that the horrific, nearly 20-minute execution of convicted murderer Dennis McGuire using a previously-untested cocktail of drugs did not violate McGuire 8th Amendment rights, despite admitting that the method "might cause discomfort". In this case, McGuire suffered "ten minutes of irregular breathing and gasping" as his body slowly suffocated.
Judge Frost sided with the State despite admitting that the execution would amount to experimentation, reasoning that "Ohio is free to innovate and to evolve its procedures for administering capital punishment."
Certainly, one could argue that no execution is truly "pain-free", as inmates spend an average of 178 months (14.8 years) in prison between sentencing and execution - time often spent almost entirely isolated from other inmates, in a state of perpetual uncertainty as to when it'll be "their turn". The psychological agony, in addition to the well-known physical dangers of a prison system in which 600 inmates are raped each day, probably amounts to a "cruel and unusual punishment", but I'm no scholar.
At this point, I think it's important to recognise a few basic facts about capital punishment:
1) It's expensive - It can cost a state up to 10 times more to execute a prisoner than incarcerating them for life. The State of California estimates that their death penalty policy cost them approximately $137m each year, while ending the practice would cost around $11.5m per year - a savings of $125.5m.
2) It isn't a deterrent - the murder rate in states with the death penalty is 46% higher than in states that have ended the practice, and the US murder rate as a whole is significantly higher than in all Western European nations that have abolished capital punishment. Simply put, there is no academic evidence that demonstrates a direct, causal relationship between capital punishment and deterrence, anywhere.
3) It is an incredibly arbitrary and biased system - The US criminal justice system is pretty racist in general, but particularly when it comes to capital punishment. 77% of victims in death row cases were white, even though Black Americans make up almost half of all murder victims. The single most consistent predictor of whether a defendant will be sentenced to death is the race of the victim.
I think most normal, reasonably-empathetic people realise that state-sanctioned killings as a form of 'revenge' isn't right. It's a sign of a repressive, backwards society that punishes offenders based on moral outrage and unabashed vitriol - prisoners, even those convicted of relatively minor offences, are viewed as irredeemable monsters, denied any chance at reintegration into society, and deprived of many of the basic rights and privileges enjoyed by any regular citizen.
More progressive societies have the capacity to respond rationally, not emotionally, to acts that transgress moral and social boundaries - Norway sentenced mass-murderer Anders Breivik to their maximum of 21 years in prison, with the possibility of extending it indefinitely as long as Breivik continues to present a danger to society. Despite the horrors of Breivik's 2011 rampage that left 77 people dead, the Norwegian government was unwilling to make an exception to their maximum sentencing laws - even for Breivik, they will hold open the possibility of redemption and rehabilitation, as unlikely as it may be.
The difference, then, is fairly stark. In the US, criminals are considered a class unto themselves, somehow inherently different from "normal" society, and fit for only incarceration or death; in countries like Norway, criminals are normal people who have broken a law, who can be reasoned with and rehabilitated and returned to society as functioning, productive members. One of these sounds a bit more rational and progressive, don't you think?