If there are no standards ... well, there are no standards.
Want to block estate taxes? Marry your children.
Adopting your girlfriend? If there is an economic/tax incentive to do so, people will try it.
Upon what grounds could any court block it? Once they approve homosexual marriage, the polygamy angle is the next clear area -- but these other areas become equally as valid.
Thanks for rescuing the central point of my post, ClearCase.
The legal arguments in the California Prop 8 case can be applied directly to this guy's case.