James Thunder writes at The American Spectator:

"We have presumed that, if traditional marriage laws are unconstitutional, the remedy is to make marriage eligibility less restrictive and allow same-sex couples to marry. What if, instead, we chose an alternative method to meet constitutional requirements, namely, revising our marriage laws to make them more restrictive?"

The results may surprise you.

For those of you who want to get right to Thunder's eventual answer:

This thought experiment demonstrates that current marriage law is tailored to fit -- as tightly as we should dare go -- the justification of "responsible procreation" for traditional marriage of one man and one woman.

Traditional marriage reflects and upholds who we are. Biologically, we are of two genders and only women can bear children. While women can bear children without benefit of marriage, marriage does indeed provide a benefit -- in the first instance to the children, and second, to the mother, the father, and society. The focus of traditional marriage is on the needs of children, not, as one brief put it, on "the glorification of the adult self." If the institution of marriage is not focused on children, but rather, as the opponents of Prop 8 assert, on the affective emotions of the adults, then government has no particular interest in the institution because it has no particular interest in the (mere) lifelong companionship of adults.