When police officers knocked on the door of the Terrell, Texas, home of Louis W. “Bill” Conradt Jr. to serve him with warrants in connection with an online-solicitation-of-a-minor case, the experienced prosecutor didn’t answer.

After working for more than two decades enforcing the Texas Penal Code, Conradt likely knew that the law that had brought the officers to his door was one of the strongest of its kind in the nation — a statute that would eliminate any defense he could offer in a courtroom.