There are deep public policy arguments against including polygamous relationships within the rights of a civil marriage. Propietary rights, tax and estate issues, commercial and liability concerns (just to name a few) are compromised in such relationships. Similarly, the State should not allow blood relatives to marry for a variety of practical reasons.
I had been trying to frame my argument about the legal complications introduced by polygamy, but you did it for me Kly. Excellent post.
