While the law is a moral enterprise on its face, it is not possible, nor is it wise to legislate against every kind of moral wrong.For example, while it is morally wrong to deliberately harm one’s body, and smoking cigarettes deliberately harms one’s body, it is generally not advisable to deny one the freedom to smoke cigarettes by outlawing smoking.The general principle is that we should only legislate against moral wrongs that have a major impact on the common good, or interfere with the exercise of the fundamental rights of our fellow citizens.A certain measure of liberty should be left to the individual to choose even those things that are morally wrong, because outlawing that evil may result in an overall increase in evil, and because it is practically impossible for the State to legislate against every form of moral wrong, yet alone to enforce it.

Some attempt to employ this principle as an argument for the legalization of same-sex marriage.It is argued that since liberty is to be preferred to constraint unless an exercise of liberty is to the detriment of the common good, the liberty of marriage should be extended to same-sex couples (even though same-sex marriage is immoral) because same-sex relationships are not detrimental to the public good.How might opponents of same-sex marriage respond to this argument?

While it is true that we should not legislate against all instances of moral wrong, this principle cannot be employed indiscriminately.If it were, no laws aimed at prohibiting immoral behavior could be passed!The burden of proof is on the person arguing we should not legislate against this or that particular moral wrong, to show why we should not do so.In this case, it is being argued that same-sex marriage, though morally wrong, does not negatively affect the public good.Like smoking, then, it should not be prohibited.Is it true that same-sex marriage will not impact the public good in a negative way?There are good reasons to think this is false.

First, extending the institution of marriage to same-sex couples is social declaration that homosexual sex/relationships and heterosexual sex/relationships are equal.This is manifestly false.The purpose of heterosexual sex and homosexual sex are very different (the former is for procreation and recreation, while the latter is only for recreation), as well as the health risks involved with both behaviors.There are virtually no health risks for engaging in monogamous heterosexual sex, but there are many health risks for engaging in (even) monogamous homosexual acts.

Second, it is a social declaration that moms and dads are not necessary for optimal child development.There is no denying the fact that the legal recognition of same-sex couples to adopt and rear children naturally and legally follows from the legal recognition of same-sex relationships as a valid form of civil marriage (in some instances the legal right to adopt actually precedes the legal recognition of same-sex relationships as a valid form of civil marriage).Granting marriage rights to same-sex couples, then, has ramifications for child-rearing.To recognize same-sex relationships as civil marriage is a tacit admission that moms and dads are not necessary for optimal child development—that two moms or two dads will equally suffice.This is wrong.Both moms and dads are needed for optimal child development.

This argument also fails because it ignores the critical difference between allowing people to participate in certain immoral behaviors without the threat of law, and actively declaring through the law that such behaviors are legally protected.The law is a moral teacher.To enshrine something into law is to make a moral declaration about that something: that it is good, or that it is bad.To give legal sanction to same-sex marriage where such sanction did not exist previously would require the creation of new legislation to redefine the institution of marriage.This legislation would have the effect of actively declaring that our society finds same-sex marriage to be a moral good.This is utterly different than the situation we find ourselves in today, in which same-sex couples can openly engage in committed relationships with one another, but without the blessing of society.The difference is one of social approval.Allowing them to engage in committed relationships without the threat of law is to grant them liberty; sanctioning their relationships by enacting laws recognizing their relationships as valid instantiations of civil marriage is to grant them social acceptance.

Ultimately, then, the argument from liberty fails.We should not open up the institution of marriage to same-sex couples.Not only would same-sex marriage negatively impact the common good of our society, but doing so would have the implicit effect of teaching society that a moral wrong is a moral good.