The U.S. Supreme Court decides next week whether to hear challenges to laws defining marriage as the conjugal union of a man and a woman. It does so after two different electoral outcomes. In May, North Carolinians voted to amend their state constitution to protect the conjugal definition of marriage, a definition that 41 states retain. But on Nov. 6, voters in Maine, Maryland and Washington state endorsed a revisionist view of marriage as the union of any two adults.
How should the Supreme Court decide? How should voters?
We can’t move one inch toward an answer simply by appealing to equality. Every marriage policy draws lines, leaving out some types of relationships. Equality forbids arbitrary line-drawing. But we cannot know which lines are arbitrary without answering two questions: What is marriage, and why does it matter for policy?