What's wrong with polyamorous marriages? As long as everyone's honest and open with each other and there aren't wierd power dynamics in terms of religion or money, who's harmed?

Yeah, if people want to be in a consensual polygamous marriage, nobody should have the right to tell them they can't.

Nothing. If we can expand the law to make some folk's lives happier and legally easier without any harmful side effects than I can see nothing wrong with it. But people are not referring to polyamorous marriage when they use the term marriage equality.

It gets a bad rap because those who tend to participate are often from reclusive cults riddled with abuse and both forced and underage participation, though that's hardly an argument against it because that's the kind of thing law enforcement should be dealing with in any case.

The problems with poly marriage are entirely legal ones. Recall that the only thing that changed with marriage equality was who is allowed to participate with one another, every other aspect remains identical. There's the rub: there is no legal precedent for fair marriages containing more than one participant, and the current marriage laws have absolutely no ability to deal with that whatsoever. Everything from inheritance to child support, power of attorney, divorce and custody, all of it in current laws expects only two participants. Changing that doesn't demand rewrites or additions, it requires rebuilding the whole thing from the ground-up. Example: with multiple equal spouses, what do you do when one is rendered unable to make their own medical decisions and the other spouses disagree on the course of action? What do you do when someone leaves the marriage and there are children? That they are related to? That they are not related to? If that changes things then the marriage does not have equality of responsibility and is more like multiple two-person marriages all mixed up, with all the problems that would cause.

It's an unprecedented legal nightmare. The real problem is not finding public support, it's finding the legislative will to sort it out. The only solution I can see would be to create a modular marriage licence that is customised to the number of participants and other necessary aspects, allowing it to be constructed to requirement, including the popular two-person package that affords the familiar rights and responsibilities of a two-person marriage. This means dismantling the legal institution of marriage entirely and building something new. Possibility adapting from current laws of business incorporating, which deals with similar issues.

I would support that, I'm just saying that the difficulties and practicalities of putting together a workable system may be prohibitive, at the very least a very long way off. The best case scenario would, ironically, involve in part the overturning of gay marriage laws so soon after their implementation.

BM: Agreed with everything in your post but this:
Yes, it means dismantling the legal institution of marriage. No, it doesn't mean building something new in law. If you look at the laws surrounding marriage, they're heading in that way already. At least in Australia (and I think it's similar elsewhere) the legal benefits of getting married have been watered down, while the legal benefits of being in a de facto/common law relationship has been strengthened. I believe that in time the legal concept of marriage will disappear entirely. People will still have ceremonies, whether religious or secular, but it won't be recognised by the state. And all the legal ramifications you mention will be determined (largely by the courts, I imagine) as matters between two or more people, with no particular weight given to an archaic tradition. And it'll be a lot easier that way - imagine how much easier the fight to support recognition of gay relationships would have been if it didn't involve the word 'marriage'. Similar to recognition of polyamorous relationships.

I guess the common law relationships would qualify as "something new," since not everywhere has those available yet.

I think you would still need more than independently constructed contracts for each one, though. Not everyone will understand the options, lawyering up isn't very romantic and we can't risk the quality of the contract being linked to the price of the lawyer- that defeats the whole point of equality.

It is also needed for other institutions: hospitals, for example, will need an easy and reliable way to know who gets visitation rights and power of attorney without trouble, schools will need to know that the stranger who arrived to take away a kid is really one of their parents, and so forth. I don't think any modern society has properly explored the complexities yet, and so geared toward two-person relationships as society is we're bound to have blind spots setting us up for unexpected outcomes.