A question of interest to me that arose in the recent debate I had with theobromophile about copyright law was over whether it is valid to say that laws exist to enforce morality.
I have always seen it that way. Laws, to my mind, are at essence moral injunctions that we as a society have chosen to impose on ourselves. Our collective moral sensibilities dictate that murder, rape, theft, and so forth should not be tolerated. Our moral sensibilities dictate that we ought not to allow the poor to suffer when we have the power to alleviate it (yes, through government, if that is what we decide). To a fair extent we have decided that it is immoral to allow suffering to go on in other places in the world when we have the power to alleviate it.
Sometimes the moral basis of a law is not obvious on the surface, but the postulation is that if you trace the reasoning back far enough you will arrive at one. We have then a falsification test for the theory. Find one law that together with its context cannot be derived from a moral sense of ought and you will have proven the theory false. (as political theories go, it may not be possible, however, to prove it true)
The reason I am sure many of us, including myself at times, become weary whenever we hear the phrase “legislate morality” is because it is frequently used to mean legislate personal morality, that is, those actions that don’t affect others directly. We by and large do not legislate personal morality because we place such a high value on individual liberty. This, too, derives from our collective moral sensibilities.