What is the purpose of law? Is it to enforce objective standards of right and wrong, or is it to facilitate social order? Sometimes these are the same things, but what about the circumstances when they are not? Should law reflect what is right, or should it implement policies that facilitate order? Let me give a couple of examples to explain what I mean.
Let's assume for the sake of argument that all killing is immoral. Therefore abortion would be immoral. But let's say that studies have shown that outlawing abortion doesn't decrease the abortion rate. Instead the abortions are performed illegally and are dangerous to expectant mothers. Therefore if you do the moral thing and outlaw abortion, then you get a worse outcome as a result.
(That is probably a pro-left example, so let me give a pro-right one.)
Let's assume again that all killing is immoral. Therefore capital punishment is immoral. However let's say that studies have shown the murder rate to drop by 7 for every criminal executed under the death penalty. Therefore if you do the moral thing and outlaw capital punishment, then society suffers the effects of a worse outcome.
In both of my examples enforcing the "right" thing would decrease social order. So what do you think the purpose of law is? Is it to enforce right and wrong, or is it to facilitate social order?