I think we would all agree that, if there really is to be a distinction made between moral and legal wrongdoing and between the sphere of private freedom and that of public control, there must be some principle or procedure for determining what the law can and cannot forbid. If we don't have that procedure, or if we can chop and change, invoking liberty when liberty goes in our favour and "public morality" when it goes the other way, we are only pretending to distinguish law from morality. And recent experience of the UK Parliament, which is peopled by a new breed of puritans who are every bit as keen to impose their views on the rest of us as their 17th-century forebears, and every bit as keen as those forebears to claim the exemptions required by their own way of life, suggests that there is a real temptation among those who find themselves able to make laws for the rest of us, to be guided not by the love of freedom but by the morally-inspired desire to extinguish it.
The puritan is a human type - unfortunately - and to think that puritans include only churchgoers is naive in the extreme. These days, you're likely to find more true puritans at a political rally than at Mass. Political true believers can get hung up on dogmas as much as anybody, with similar results.