It stands to reason that if someone under 18 can’t legally consent to sex, then that same someone also can’t be arrested for prostitution, right? Oh so wrong. The paradox of such prosecutions has engendered the “No such thing as a child prostitute” national campaign, which has taken hold in Los Angeles. L.A. County is now considering how to punish “johns” caught paying children for sex. But San Francisco psychologist and researcher Melissa Farley has for more than two decades been more concerned about the prostitutes themselves: Rescuing them, rehabilitating them and getting politicians and prosecutors to agree that even when it comes to adults, they aren’t criminals but victims.