An understanding of the criminal “justice” system has to begin with this:
The criminal “justice” system is not about “right and wrong.”
“Right and wrong” and “legal and illegal” are entirely separate concepts. “Right” and “wrong” are moral terms, not legal terms. The fact that something is illegal does not make it wrong, and the fact that it is legal does not make it right. (Flipping those two propositions, the fact that something is right does not make it legal, and the fact that it is wrong does not make it illegal.) Something that is wrong and illegal does not become right if it’s decriminalized. Something that’s right and legal doesn’t become wrong if it’s criminalized.