system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is it so easy for people to routinely O.D. on drugs and quietly die in thier sleep, but when a state attempts an execution, its complicated, often botched, and generally controversial?

Also, vererinarians. Putting a dog or cat to sleep is a simple procedure performed every day with no complications. 

Why is the business of executing people so incredibly complex, with "cocktails" of lethal drugs required to be administered over multiple doses. Why not just inject a large dose of morphine or some other opiate to lull the person, have them fall asleep, and simply stop thier heart?
gpt
People OD on illegal and legal drugs.  Often the death is not quiet and clean.


The government isn't going to use illegal drugs.


Legal drugs that kill you nicely aren't sold to governments by the drug companies - they don't want to associated with the death penalty.

The cocktails are of legal drugs that, individually, don't kill you nicely.  The hope is that the combination will.