With Utah unexpectedly at the center of a new fight over state bans on same-sex marriage, articles in The New York Times and elsewhere have explored how the state is trying to defend its ban. One unexpected argument is to cite Grutter v. Bollinger, the Supreme Court's 2003 ruling upholding the right of public colleges to consider race in admissions. "Society has long recognized that diversity in education brings a host of benefits to students," says Utah's brief to the Supreme Court, citing Grutter. "If that is true in education, why not in parenting? At a minimum, the state and its people could rationally conclude that gender diversity -- i.e. complementarity -- in parenting is likely to be beneficial to children. And the state and its people could therefore rationally decide to encourage such diversity by limiting the coveted status of 'marriage' to man-woman unions." If this argument should go anywhere, it could present interesting challenges for Supreme Court justices like Antonin Scalia (a fan of gay marriage bans who dislikes the Grutter decision) and Ruth Bader Gisburg (a fan of the Grutter decision who dislikes gay marriage bans).