It is not lawful in the United States to make a polygamous marriage. But what about a polygamous marriage made in another country that is lawful there? Should U.S. courts recognize it?
Eugene Volokh raised this question in the context of whether U.S. courts will recognize gay marriages made in Canada. He mentioned two cases: People v. Ezeonu, 588 N.Y.S.2d 116 (1992), and In re Estate of Bir, 83 Cal. App. 2d 256 (1948).
Ezeonu deals with a man who was criminally charged with the statutory rape of a 13 year old girl. One of the defenses to statutory rape is that the defendant was married to the complainant. Ezeonu attempted to raise this defense. The problem was that the complainant was his second wife. The marriage was lawful where made, in Nigeria. The court said that foreign marriages would only be recognized as valid if they were not contrary to public policy in New York and it considered polygamy to be "repugnant to public policy". This particular marriage (i.e., to a 13 year old girl) certainly strikes one as questionable at best (and according to this story the circumstances are indeed repugnant) but the judge seems to have felt that even a polygamous marriage involving all consenting adults was equally repugnant.
The other case, Bir, deals with the division of the estate of Dalip Singh Bir, who died intestate and had two wives claiming portions as heirs. After an extensive review of the precedents, the court decided that the polygamous marriages should be recognized as valid for the purposes of succession.
As Professor Volokh notes, the two decisions are not contradictory since the California Court of Appeal did not rule that polygamous marriages were valid for purposes of cohabitation, which was the question at issue in Ezeonu.
Bir is particularly interesting for the precedents that it cites for its position recognizing polygamous marriages as valid for purposes of succession. I was not able to track down all of the cases cited, since most of them are very old, but I did find two that are directly on point, both dealing with Native Americans. These are Ortley v. Ross, 78 Neb. 339 (1907), and Hallowell v. Commons, 210 F. 793 (8th Cir. 1914). Bir also cited Caballero v. The Executor, 24 La. Ann. 573 (1872), which deals with the validity of a foreign-made interracial marriage.
There are a couple of interesting points here. First, none of these cases seem to involve Muslims. Polgamy is common in West Africa among people of all ethnic groups and religions and is even recognized by some Christian churches in Nigeria. Ezeonu's religion isn't mentioned in the ruling; he could be animist or even Christian as well as Muslim. Bir was Sikh. And of course, Native Americans have their own religious traditions. Bir mentions a Canadian case, Yew v. Attorney General for British Columbia, 1 Dominion Law Reports 1166 (1923), which involved a Chinese polygamous marriage.
Although Americans tend to associate polygamy exclusively with Islam, it has in fact been practiced in many if not most non-Western cultures. It also appears in the Bible; prophets such as Abraham, Moses, David, and Solomon, among others had multiple wives (see Polygyny in Christianity for links about the support for polygamy among Biblical Christian groups).
The other point was brought to my mind by the interracial marriage case. Today, we consider it obvious that interracial marriages should be allowed. We're also moving towards greater recognition for same-sex couples (as Lawrence v. Texas shows). Perhaps in the future, Americans will come to accept polygamy as well on the grounds that consenting adults should be free to choose whatever family structure they want as long as they are not harming anyone.