> For example, MHA found that there was a 66 per cent reduction in the average net weight trafficked for opium in the four-year window after the mandatory death penalty was introduced in 1990 for trafficking more than 1,200g of opium.
> In the four years after the death penalty for trafficking more than 500g of cannabis was introduced in 1990, there was "a 15 to 19 percentage point reduction in the probability that traffickers would choose to traffic above the capital sentence threshold", said Mr Shanmugam.
https://www.channelnewsasia.com/news/singapore/death-penalty...
Granted, the deterrence value of capital punishment as applied in most nations, such as the U.S., has been shown to be negligible. Most countries, especially in the 21st century, just don't have the stomach to apply capital punishment strictly enough to make it worthwhile. And for good reasons, I might add. But if I were creating a country from scratch, before certain patterns of crime and social dynamics became endemic (that is, firmly rooted in the economic life of certain classes such that they would, as a group, be systematically grossly disproportionately punished), I would absolutely employ capital punishment.
I think in the U.S. we tend to assume that poverty and violence go hand-in-hand. And so to punish violence is to in some sense punish the poor. But if you look at poverty around the world, violence is not a necessary consequence of poverty. There are many places where even desperately poor communities experience much less violence than some of the richest towns in the U.S. Ultimately it's a function of the wider culture and its predisposition to violence. If you can use capital punishment to forestall societal changes (e.g. drugs trafficking, use of guns in crimes) that invite pervasive violence, you can achieve a more just outcome for everybody. But in practice you probably can't use capital punishment to put the genie back in the bottle; certainly not alone.