ome years ago, I heard that Matt Gaetz had been accused of having sex with an underage girl. Much later, I understood that the claim had turned out to be false and had been dropped. But now, following Gaetz’s nomination as Attorney General, it has reappeared in the guise of a House Ethics Committee investigation and attendant newspaper leaks. Headlines have been full of salacious references to sex with a 17-year-old. I wondered why that was ever a matter for criminal investigation, since in most states 17 would be above the age of consent. But the age of consent is...