Posner’s tone is not fatigue but Five-Hour Energy. He does not rebut arguments against same-sex marriage, but rather (to paraphrase an old Southern threat) beats them to a pulp, puts the pulp into a sack, and then beats on the sack.

Same-sex marriage bans, he writes, violate the 14th Amendment’s prohibition on “deny[ing] ... the equal protection of the laws.” He chides the state defendants for ignoring the long history of discrimination against LGBT people:

One wouldn’t know, reading Wisconsin’s brief, that there is or ever has been discrimination against homosexuals anywhere in the United States. The state either is oblivious to, or thinks irrelevant, that until quite recently homosexuality was anathematized by the vast majority of heterosexuals (which means, the vast majority of the American people), including by most Americans who were otherwise quite liberal. Homosexuals had, as homosexuals, no rights; homosexual sex was criminal (though rarely prosecuted); homosexuals were formally banned from the armed forces and many other types of government work (though again enforcement was sporadic); and there were no laws prohibiting employment discrimination against homosexuals.

Sexual orientation, he writes, has all the earmarks of what constitutional lawyers call a “suspect classification,” meaning a trait like race, religion, or sex that automatically triggers judicial suspicion when employed in law. Such classifications, he says, are based on “immutable or at least tenacious characteristic of the people discriminated against (biological, such as skin color, or a deep psychological commitment, as religious belief often is, both types being distinct from characteristics that are easy for a person to change, such as the length of his or her fingernails).”

But Posner does not push ahead of the Supreme Court by holding that restrictions on LGBT people should receive “heightened scrutiny” like those based on race, religion, or sex. Instead, he focuses on the reasons the two states gave for discriminating against LGBT people in marriage, which strike him as not just irrational but nonexistent. “The governments of Indiana and Wisconsin have given us no reason to think they have a ‘reasonable basis’ for forbidding same-sex marriage,” he writes.

Posner finds the states’ justifications so irrational that he almost becomes unhinged himself. Is the ban in place to encourage responsible procreation by heterosexuals? “Heterosexuals get drunk and pregnant, producing unwanted children; their reward is to be allowed to marry. Homosexual couples do not produce unwanted children; their reward is to be denied the right to marry. Go figure."

Is the ban really about “procreation” at all? Posner dives deep into a truly obscure issue: Why does Indiana permit first cousins to marry, but only if they are too old to have children? Why, for that matter, does the state refuse to recognize out-of-state same-sex marriages, but does grant recognition to out-of-state marriages between cousins? “Indiana has not tried to explain to us the logic of recognizing marriages of fertile first cousins (prohibited in Indiana) that happen to be contracted in states that permit such marriages, but of refusing ... to recognize same-sex marriages (also prohibited in Indiana) contracted in states that permit them.”