18 U.S.C. § 2709(a), (b)(1). 4 Congress has provided for mandatory nondisclosure of Treasury Department orders requiring financial institutions to take action the government finds it “necessary to carry out the purposes” of currency-transaction-reporting laws, 31 U.S.C. § 5326, plainly implicating the scope of the government’s authority. Case 1:14-cv-09763-VM Document 42 Filed 07/31/15 Page 10 of 18 7 Nor is it true that the “breadth” of the nondisclosure order “is not consistent with an interest in protecting the effectiveness of techniques.”