legislating morality

The original intent of the concept "You cannot legislate morality" was to convey the idea that passing a law prohibiting a particular kind of activity would not necessarily eliminate such activity. The point of the phrase was that laws do not ipso facto produce obedience to those laws. In fact, on some occasions the legal prohibition of certain practices has incited only greater violation of established law. "Prohibition" is an example.

The contemporary interpretation of legislating morality differs from the original intent. Instead of saying the government cannot legislate morality, it says the government may not legislate morality...

If we take this kind of thinking to its logical conclusion, we leave the government with little to do. If the government may not legislate morality, its activity will be restricted to determining the colours of the state flag, the state flower, and perhaps the state bird. (But even questions of flowers and birds may be deemed "moral" as they touch on ecological issues, which are ultimately moral in character.)

The vast majority of matters that concern legislation are, in fact, of a decidedly moral character. The regulation of murder, theft, and civil rights are moral matters. How a person operates his automobile on the highway is a moral issue since it touches on the well-being of fellow travellers.

- R. C. Sproul, How Can I Know God's Will?

of course, what should or should not be legal is a separate issue altogether.

the question is not whether the government can legislate morality. the government not only can legislate morality, but does legislate morality. rather, the question is how the government should legislate morality.