Considered too cruel to be used by vets because of the clear signs of distress shown in animals to which it was administered. But this guy says it's good enough for humans!
It's important that a prisoner not just be killed, but can feel themselves dying, apparently.
I understand why you would think this seems peaceful. But we have no idea whether it is, anyone claiming otherwise is bullshitting or lying, and the entire idea of "humane" execution is an oxymoron to begin with.