Did you know that there are 40,000 underground polygamists in the U.S.? And a world religion, Islam, allows plural marriage, plus multiple spouses have been present in human cultures forever. So shouldn’t polygamy be legal? Yes, because having multiple wives is a religious right and should be protected under the right to contract and/or substantive due process.

So what’s wrong with multiple wives, especially if they’re consenting adults? After all, consenting adults should be free to have group marriages, gay marriages, mail-order marriages, marriages for convenience, marriages for money, or any other kind of marriage. This is just freedom of contract, a right found in Article I, Section 10 of the U.S. Constitution which states that “No State shall enter into any … law impairing the obligation of contracts.”

The right to contract for business is fundamental to the free enterprise system and so is the right to contract for social relationships like marriage. Family law in every state allows for social contracts in the marriage and family context. There are pre-nups, post-nups, and separation agreements. The law encourages divorcing parties, and business parties, to freely contract to arrange and organize their affairs in a consensual fashion. Freedom of contract affirms the dignity and autonomy of the individual and is the mark of a legally and economically sophisticated society.

There’s another reason to allow plural marriage: religious freedom. How dare the state or feds, or anybody else, tell worshipers how to practice their religion? Clearly if a fundamentalist sect threw virgins into volcanoes, the state could step in. But when there is no victim and thus no legitimate state interest, only consenting wives who’ll tell you they’re in of their own volition, then individual freedom should reign.

Criminalizing victimless sexual and intimate relations like this is misguided. I say “victimless,” because criminalizing some private relations, like domestic violence — where there really is a victim — is acceptable. But laws regulating consensual relations between adults, like laws against polygamy, prostitution, sodomy, fellatio and the like, should be repealed.

Alternative lifestyles have always met with criticism. Opponents of early divorce laws thought they would legalize polygamy as people remarried. And cohabitation and having kids out of wedlock used to be spurned. All are now mainstream. Alternative families take many forms and should be protected by law (up to and until there’s a true victim.) The state, in general, should be neutral on lifestyle and moral issues.

“Bigamy” is the legal crime, under which people can be prosecuted for the act of marrying one woman while still married to another, while “polygamy” is having multiple wives. The modern term for more than one spouse is “plural marriage.” “Polyandry” is having multiple husbands. Polygamy is more common in human cultures than polyandry.

Polygamy is legal in Muslim countries today, although fairly rare as the husband must be wealthy enough to support his wives. And polygamy was a tenet of the Mormon Church from 1840 until 1890 when the Church ended it because of federal threats to withhold statehood from Utah (achieved in 1896). Old Testament prophets took multiple wives and anthropologists will tell you that polygamy has been in human cultures throughout history.

Many accurately point out that some polygamist’s wives are as young as 13 when they were married, which is illegal. (The age in Washington to marry without parental consent is 17.) But marrying at age 13 is legal in many states–with the consent of the parents–and is legal in some foreign countries. But whatever the age of consent is determined to be—and this is important because a marriage becomes statutory/child rape if the girl is too young—plural and unorthodox marriages after this age should be legal.

It’s often been said that “your rights stop at the tip of my nose.” And similarly, the right to an alternative lifestyle stops at the age of consent. The right to contract is an adults-only right. Minors and mental incompetents don’t qualify.

But outside of this, freedom of marriage should be the rule. Gay, polygamous and other alternative marriages should be legal private contracts, with or without the state. Absent coercion, duress, fraud, incapacity, insanity, underage, criminal conspiracy or other traditional common law contract defenses that can justify breaking contracts (or prevent enforcing such contracts), such alternative relationships should remain free of government regulation per substantive due process.

Once legal, polygamy would come out from the underground where it is harder to prosecute the real crimes that do occur in polygamous communities. With polygamy illegal, polygamists are reluctant to call police regarding real crimes like domestic violence, false imprisonment and rape.

And note that a human can’t marry his pet because animals don’t have rights and responsibilities under the constitution and American law wouldn’t recognize such a marriage. You can set up a trust for your pet, but you can’t marry it. Nor could you marry an inanimate object.

A man is not a criminal for having 5 wives. He may be bad for failing to pay the state back for welfare received, and he may be a legitimate criminal for marrying and having sex with an underage girl, or for rape, but absent that, the mere status of polygamy should not be a crime, but a protected right.

Jeff E. Jared is an attorney and political writer in Kirkland who writes from a libertarian and law-and-economics perspective.