I'm not sure there is such a thing. All laws ultimately come down to morality.
That's crazy, I certainly hope not.
Let's take the simplest example: Theft. We all agree it's immoral, but that's not why it is illegal. It's illegal for economic reasons, for reasons of justice, for policy that shows punishing theft results in a better society, and dozens of other reasons.
My issue with morals is they are too loose and cannot be litigated.
First, there is no one set of morals. Even people within the same religion or society have vast disagreements over morals. Are gay relationships moral? Is sex before marriage moral? Is killing an innocent animal for clothing moral? Is worshipping satan moral? There is no agreement on morals, and probably won't ever be.
Second, even if there some kind of consensus on morals, where do you go to bring challenges on moral grounds? Say there is no law against adultery, but we all agree it is immoral. If your spouse cheated on you, who can help on moral grounds? How do you fix the moral wrong?
I think morals serve very important purposes: (1) They are easy-to-understand guideposts for small children to learn to become good functioning adolescents, who can then learn more complicated rules of society. (2) They are wisdom that can be passed down from generation to generation, due to their simplicity, and thus have generally outlast any organized set of laws. (3) They are a sanity check against complicated situations, where taking a step back and considering the morals may be a good way to address something which is otherwise too large and has too many moving pieces.
So I am not arguing against the idea of morals. I just think we should be honest when making arguments. In my OP in the other thread that was quoted above, I was responding to an assertion that the estate tax is immoral. Sure, it might be to some people, but that version of morals does not override the very real and tangible socio-economic, political, and historical reasons for having an estate tax.