Much work has gone into making sense of Justice Kennedy’s famously unconventional use of the rational basis test in Lawrence v. Texas. But why did invalidating state sodomy bans require any doctrinal innovation? Shouldn’t Lawrence have been an easy case under already-existing law? After all, legislation must serve a secular purpose to meet the Establishment Clause test laid out in Lemon v. Kurtzman, and the bans had no rationale but a pan-Abrahamic homosexuality taboo. So hadn’t the bans been unconstitutional since Lemon—that is, some thirty years before Lawrence?
Until Lawrence, there was an anomaly at the heart of the Lemon test: Courts took morality enforcement for granted as a secular purpose, irrespective of whether that morality had any nonreligious rationale. This prevented the Lemon test from reaching one of the areas that needed it most: so-called “morals legislation.” Hence Lawrence is in effect an Establishment Clause case despite purporting to sound in due process. For the rule of decision it applied in invalidating the bans for lack of a secular purpose is none other than the familiar first prong of the Lemon test: Legislation must do more than codify creed.
In reaffirming that religious belief never suffices as a basis for legislation, Lawrence gave Lemon the breadth it always should have had. When it applied the secular purpose requirement to morals legislation, Lawrence vindicated the cultural choice implicit in the First Amendment’s nonestablishment rule—our precommitment to a legal system grounded in reasons that are open to all Americans.