Guillotine is the only way to be sure. It’s 100% guaranteed and there is no time for the convict to experience pain.
The only reason I can think of a the reason why the left is against the death penalty, like everything else, it has to do with emotion. The walk to the death chamber, the strapping in, the last right. All of this takes an emotional toll on the convict.
We have to be more humane. I would suggest, when the convict goes to sleep, pump nitrogen into the cell. Convict will never wake up.
I am in favor of Nitrogen.
It is quick and painless.
If we want it to be more interesting, we could switch and use liquid Nitrogen.
That might be painful...
It would be very difficult for them to ban liquid Nitrogen.