Probably the strongest form of the "going against legal X leads to illegal X" is that "if society doesn't address the causes that make people want X and just ma

Probably the strongest form of the "going against legal X leads to illegal X" is that "if society doesn't address the causes that make people want X and just makes it a criminal offence, we'll still see a lot of X, plus we'll have a lot of folks in prison". For example with murder we have many cases of vigilantism, the cause was a broken police/justice system. Every kind of substance crime? War on Substances! And it's a total failure. "Tough on X" ("enforcement") sounds good, but our whole history is about how tough never really works. (Law and order, machismo, denying and ignoring real causes, and putting on a big show about the effect, those are the magic ingredients to totalitarianism.)