Where the law over-reaches to criminalise mere vice, it should be beaten back, on the basis that vice is not crime, and where no violation has occurred against another person or their property, the law should leave well alone. Elsewhere we find morality conflicting with law, at least for some, with a prime example of controvery being the continued categorisation of assisting suicide as manslaughter - a very series property rights violation (!).
Leaving aside any dispute over the categorisation itself, (I would say it is indisputable in natural law, due to the inalienability of one’s property in oneself), those who seek to change the law do so because they believe assisting suicide is a moral act and believe that because it is moral it should be lawful.
Opponents dispute the moral case, arguing that it can never be moral to assist in suicide. There can be no resolution of the moral argument, due to the subjectivity of morality. My argument for keeping the law as is, would be different. I would leave aside the moral issue. Manslaughter is unlawful, and should remain so. Let the discretion of the jury and the judge bring the necessary measure of equity. This alone can and must suffice to ensure that the iron rule of the law is tempered with mercy.
Expecting the law to concord exactly with morality is a red herring that stinks at both ends. A more extreme example of morality, its subjectivity and its irrelevance with regard to questions of lawfulness is presented by phenomenon of 'honour killing'. Whatever significance we should attach to the evident fact that some people consider it moral to murder their own flesh and blood, the crime stands!