In modern America, sex is increasingly where it should be: outside the reach of government. Anti-sodomy statutes have been tossed by the Supreme Court. Contraception is widely accessible. Anyone with a computer can gorge on pornography without fear of prosecution.

Same-sex marriage has been legalized in 18 states and the District of Columbia. Now another step has been taken to expel police and legislators from the bedrooms of consenting adults: a federal court decision striking down a key element of Utah’s ban on polygamy.