The National Security Agency went into Judge Richard Leon’s courtroom with a powerful precedent on its side. In its 1979 decision in Smith v. Maryland, the Supreme Court held that individuals do not have a “reasonable expectation of privacy” in the numbers they dial on their phone because “[t]elephone users . . . typically know that they must convey numerical information to the phone company; that the phone company has facilities for recording this information; and that the phone company does in fact record this information for a variety of legitimate business purposes.” When someone voluntarily discloses information to a third party, they assume “the risk that the information would be divulged to police.”