As of Saturday, your options for owning an unlocked phone become far more limited. You can ask your carrier to unlock it—and good luck with that—or you can pay a premium to manufacturers like Apple or Google for a new unlocked phone. You just can’t unlock your phone yourself—at least, not legally. That decision was made not by voters, the courts, or even Congress. It was made by one man, 83-year-old Congressional Librarian James Hadley Billington, who is responsible for interpreting the meaning of the Digital Millennium Copyright Act (DMCA). Billington decided last October that unlocking your phone yourself is...