OOC: I don't want to derail this too much, but hangings were supposed to break the neck of the sentenced, not strangulate them. That was why people were dropped. The guillotine eliminated the room for error (And made executions egalitarian).
On topic, capital punishment is already effectively banned in Preventing the Execution of Innocents. Even the Int'l Criminal Protocol won't change that, the line allowing the death penalty in PEoI and ICP are functionally identical.