Is Sexual Morality Beyond the Scope of Civil Law?

 A commenter, Gabriella Valente, left a very interesting objection in the combox on my post You Can't Legislate Morality...Can You?. In that post I set out to refute the oft heard objection that we "can't impose our values" or that we "can't legislate morals." Ms. Valente respectfully and thoughtfully disagrees. Her comment, in full, was:

The flaw in your argument is that the examples you use are all laws meant to protect and keep people from harm. If by sexual morality, you are speaking about acts between consenting adults, these acts do not place individuals in physical danger, therefore you can not equate them with murder, rape, etc.

When you say you are advocating sexual laws, does that include laws against adultery, fornication and divorce, or are these laws to only be aimed against same sex acts? You must understand that most people consider it hypocritical when there is a demand for laws against homosexual acts and not as strong a demand for laws against heterosexual acts.

Furthermore, with sexual laws you are seeking to impose religious values, since they do not protect individuals or property. Would you agree with the imposition of sharia law? Muslims also have rules about the proper conduct of individuals in the sexual sphere. How would you react if they demanded civil laws which supported their religious beliefs? (I know there are Muslim countries where sharia law is civil law, but those are countries which are not based on the constitutional separation between church and state.) When people see Christians demanding that the rules of their individual denominations be ensconced in civil law they see that as an attempt to violate the separation of church and state. They react the same way most Christians would react to the imposition of sharia law.

You'll note, if you've read the first post, that my original argument (that we legislate morality all the time, so arguing that we can't legislate morality when it comes to sexual morality is a case of special pleading) isn't challenged. Therefore, for the purposes of this reply, I'll assume Gabriella and I agree that a society can and indeed must legislate morality. However, Gabriella appears to part company with me when I extend realm of possible legal action to the sexual area. She gives a few reasons for this, which we can look at in turn.

Paragraph 1 - Sex acts between consenting adults do not harm anyone, laws should only be made to directly protect people and property, therefore sexual morality cannot be legislated.
This is the underlying argument of the first paragraph. Does it hold up under examination? Are either of these premises defensible? I don't think so. In the first place some sex acts between consenting adults do in fact harm people. We need only to think of adultery, which harms the spouse cheated on or a sex act where one member knowingly has AIDS, a case of public indecency where the couples consensual act is done in view of passers by, or any number of other examples to quickly disprove this premise. Further something like prostitution or pornography seem to cause no harm to anyone other than the consenting adults, yet most people would find laws against at least the former of these to be within the scope of government. The second premise is equally indefensible for laws are made every day that do not directly protect people or property. Tax laws, laws demanding equal service for people regardless of race, laws outlawing the hunting of endangered animals, even laws limiting the size of Big Gulps! Many laws are meant to protect people from harm, but others prohibit consenting adults from all sorts of activities. With both premises proven false, the conclusion, obviously, remains unproven.

Paragraph 2 - You are hypocritically singling out homosexual acts for legislation. Hypocrisy is wrong. Therefore laws against sexual immorality are wrong (if they are aimed solely at homosexuals).
I never addressed homosexual acts or persons in the original post, so I'm not entirely sure where this is coming from. This paragraph is a red herring.
 
Paragraph 3 -  Laws against sexual immorality are an imposition of religious values. Imposing religious values is wrong. Therefore, laws against sexual immorality are wrong.
The thrust of my original article was that all law is an imposition of someone's values. We impose the value of the dignity of a woman on the rapist who thinks women exist solely for his pleasure. We impose the value of personal property on the thief who feels like taking his neighbor's car as his own. We impose the value of the right to life on the murderer out for revenge. In fact, law can almost be defined as the imposition of values through the force of the civil government. Therefore, because all law is "imposing values," then "imposing values" cannot be an objection against a particular law.

Maybe only "religious values" are beyond the scope of legal enforcement. In some cases, I'd agree with this (at least for our society*), but certainly not in all cases. Should the government lock up people who refuse to attend weekly Mass? Of course not. Should there be a law against eating meat on Fridays in Lent? Again, no. These are purely religious acts, but not all "religious values" are of this kind. The 10 Commandments, clearly a major source of "religious values" for Christians, forbid things like murder and theft along with things like adultery and idolatry. Does that mean that supporting homicide and larceny laws should be struck down as an "imposition of religious values"? Of course not, because there are also non-religious reasons to have laws against murder and theft. We can know that we should not kill an innocent person through the natural law (i.e. through knowing the nature of what a person is). So we have to ask whether having a law against sexual immorality would be based solely on a religious prescription or whether we can know it is wrong for women to sell their bodies, men to cheat on their wives, etc. also through reason. Of course, the answer to this is a hearty "yes" making these laws more like a law against the Fifth Commandment (Thou shall not kill) than like a law against the Second Commandment (Keep Holy the Sabbath). Therefore, sexually immoral acts could also properly be legislated against because they are not forcing religious activity, but are enforcing moral activity (which all law is an attempt to do).

That doesn't necessitate outlawing all (or any) immoral sexual acts, but it means we can legitimately do so. Neither my original post nor this one is arguing for specific sexually immoral acts to be outlawed, but we shouldn't dismiss such laws a priori based on some nebulous concept of "not legislating morality" or even of "not imposing religious values". There might very well be good reasons to not legislate against certain sexually immoral acts, as we don't necessarily make illegal all immoral acts, but these reasons need to be applied on a case by case basis, as any attempt to classify sexual acts as in principal beyond the pale of law is bound to fail.

* "At least for our society" because it is conceivable that such laws could legitimately exist in a confessionally Catholic country. Historically, for example, Charlemagne outlawed the eating of flesh for all of Lent, on pain of death (cf. Capitularies, 4)