If there’s enough insistence on “humane” (never minding the victim), then use a nitrogen tank/mask: noninvasive, condemned simply breathes 100% that of which the rest of us breathe 80%, dozes off, and doesn’t wake up. I don’t get this obsession with injecting chemicals when simply “filtered air” (removing O2) will do so cleanly & painlessly.
My only concern with “bullet or rope” is the result is messy and someone has to clean it up. Suppose we can leave that job to the next person in line for it.
Air tight cages filled with nitrogen is an execution method used by pest removal specialists here in urban Virginia. State law forbids catch, relocation and release.
The nice thing about the nitrogen gas execution method is that there is an extremely abundant, no cost supply of the gas. So no possible interference with the supplier by groups opposed to the death penalty like there has been with lethal injection drug suppliers.
Or carbon monoxide - perp just goes to sleep and never wakes up. Or overdose of sleeping pills. Etc. Lots of painless ways. The reason we use lethal injection is because anti-death penalty types pushed it as humans knowing full well it is anything but hunane. The plan was then to point at botched executions to push for a ban of the death penalty or at least make it very expensive. IOW this case is an example of their strategy.
Would you use medical grade nitrogen or just welding grade?