If you are accused of a crime, you are entitled to the presumption of innocence. But in the age of #MeToo, people accused of sexual misconduct are subjected, at least in the court of public opinion, to a presumption of guilt. Worse, a claim of innocence—even a provable one—is itself treated as an offense, an assault on the accuser and on “survivors” in general.

Four years ago, a woman in her mid-30s accused me of having sex with her when she was underage. I produced incontrovertible evidence that I never met the accuser—including...