I had a buddy in high school who was a fierce Navajo patriot. He bitterly resented what had become of his people. I needled him once on how much better off the Navajo were now with roads, and medicines, and aqueducts, and things. His voice got strangled and he could hardly say anything. He finally choked this out: “before you white men came, when we caught an adulterer we had horses drag him to death.”
If I had to bet, I’d bet that the Navajo didn’t really used to do that, or if they did they didn’t do it to all adulterers, male and female, in-group or out-group, alike. But that’s not the point. Adultery is something that matters a lot to people. It hits them in the gut. And widespread tolerance of adultery is an acid to the institution of marriage. But our law hardly does anything about it.
Today Maggie Gallagher proposed a revived adultery tort (alienation of affection) that would make the other man or the other woman liable to the wronged spouse. Something like it sounds like a good idea to me.
I would also favor making adultery a prominent factor in determining custody in a divorce. Making adultery a crime again has its attractions to, though whether we should have laws on the books that rarely get enforced is a question.