I've thought about it.

I am uncomfortable with saying that any committed relationship among adults should be illegal. That would mean of course that not only polygamy should be legal, but polyamory in general, whatever the membership.

As with all relationships there should not be a coercive quality to the relationship, which can be present in monogamous relationships too.

Certainly people shouldn't be punished for it.

But how and if the relationship should be recognized by the state, I don't know. Being recognized as family for health visitation seems a no-brainer, but how do you handle children legally? Do all non-biological parents adopt all children? In cases of a member of the relationship leaving, how does child support get handled?

On another front, do we now have a maximum number of people covered under a family health insurance plan? Would we have to say "for 10, you need two plans"? Then what about the odd "quiver full" movement of having lots and lots of kids. Why should they be treated differently. Of course, we should be under a medicare for all system, but sadly I don't see it happening soon.

So I guess I'm saying that as a concept (again, not "one husband, many wives" but "more than two adults" it shouldn't be outlawed.

But as to how it might work pragmatically in American society, it's beyond me.