I am not up to date with US lethal injection, but weren't the changes in lethal injections in the US "yeah, it's still a painful death, but we added muscle relaxants so it looks peaceful on the outside and acceptable to the public?"

The changes are of the form that nearly every legit manufacturer of the cocktail refuses to produce it for the purposes of capital punishment.

https://www.npr.org/2015/03/11/392375383/states-scramble-to-...

I think there's always been a paralytic involved. The idea was to knock the person out with a barbiturate, then stop the breathing with the muscle relaxant, and finally stop the heart with a bolus of potassium chloride.

It's not so much to pretend it's peaceful, as it's a error in how the drugs are administered and availability of appropriate drugs.

This is exactly my point - why do something so complicated when many people die quietly in their homes from CO poisoning? Let's just setup a CO poisoning chamber to do the same thing.

Or nitrogen as the article describes. Or a fatal overdose of a pleasant drug like morphine?

Even the guillotine is quite humane, though gory.

I never understood it either - there must be some crazy reason though.

Sadism, mostly. The electric chair was painful enough but too picturesque, which makes it easy to rally against. The injections solve that problem whilst still inflicting immense pain. Which is supposed to be good, because these damn criminals had it coming. Or something.

Many argue that the deliberate cruelty is the point. Also stigma around gas chambers.

Some states are experimenting with Nitrogen

Article from NYTimes from 2018: https://web.archive.org/web/20210704140110/https://www.nytim...

Needless to say, bringing back gas chambers is a hard sell.

Isn't Arizona planning to start executions in gas chambers again using Zyklon B?

They've always used hydrogen cyanide (HCN) gas, typically produced from potassium cyanide pellets dropped into hydrochloric acid. Zyklon B is just HCN.

Edit: not HCl, H2SO4.

Or just carbon monoxide. The thing people are so paranoid over in their homes because it is a silent killer.