I imagine that most layers are just doing their job and getting paid for it. Bringing morality into that equation makes no sense in a legal system that has little to nothing to do with morality.
Ethics is a matter of philosophy, which has a bit more going for it than just being composed of raw, uneducated opinion.
You are thinking of morals. That is a matter of opinion
A system that didn't need to hold a trial or give the mob boss a lawyer would be irredeemably immoral but one in which they go free is a shittier world. I don't envy anyone trying to remain moral while walking that line. I don't see how anyone who specialized in such clients could live with themselves.