Why same-sex marriage (or equivalent civil unions) are necessary

The California Supreme Court is currently considering whether to extend parental rights and responsibilities to same-sex former partners who raised children together prior to separating.  Two adults of the same gender raise children together, and then they separate.  In one case (also described in this NYT Magazine article from last year), the custodial adult refuses to allow the other adult to see the child.  In another case, the non-custodial adult refuses to pay child support.  These cases present both sides of the parenting coin: rights and responsibilities.

A number of thoughts:

1.  This would be much less of an issue if states recognized same-sex marriage or civil unions (as California now does).  If the couples had married or unioned, their rights and responsibilities would have been clear.  And if they had chosen not to marry or union, their rights and responsibilities would have been clear as well: the very same rights and responsibilities as heterosexual couples in similar situations.

2.  These cases demonstrate precisely why heterosexist marriage laws are not simply discriminatory on the basis of sexuality, but also on the basis of gender.  The rights and responsibilities of one adult depend on nothing other than the gender of the other.

3.  My concern is less for the adults here than it is for the children.  Adults make difficult (and sometimes poor) decisions all the time.  If they alone had to suffer the consequences of their decisions, then so be it.  But the primary people suffering here are the children.  For those who believe that marriage is primarily for the welfare of children, what would you say to the children of these relationships?  These are children who are lacking financial support, and children who are no longer permitted to see a parent who has raised them.  I understand that many conservatives believe that children do better when raised by two heterosexual parents.  (I won't take the time now to attack that claim; for the purposes of this discussion, I will accept it.)  But wouldn't the children in these cases be better off with two homosexual parents who are responsible for them than they would be with just one parent?  The reality is that there are thousands upon thousands of same-sex couples who choose to raise families together; and there is nothing that can stop them.  By denying them the opportunity to marry or union, their children lose.

Marriage is a conservative institution.  Society has an interest in encouraging people to become legally and socially responsible for one another, and especially for children whom they choose to bring into this world together.  That is the role that marriage plays, and that is why it should be provided to same-sex couples.  And yet, for social conservatives, virtually the only thing that matters in determining whether a couple may marry is the relative contours of each partner's genitals.