Can someone tell me what law the leaker broke?

[brooklynite]

33. Likely theft of Government documents...

...on the assumption the leaker wasn't entitled to a copy.

Section 641 of Title 18 prohibits theft or receipt of stolen government information as well as theft of the documents, computer discs, etc., that contain the information. United States v. Fowler, 932 F.2d 306, 309-10 (4th Cir. 1991); United States v. Girard, 601 F.2d 69, 70-71 (2d Cir.), cert. denied, 444 U.S. 871 (1979); United States v. DiGilio 538 F.2d 972, 977-78 (3rd Cir. 1976), cert. denied sub nom. Lupo v. United States, 429 U.S. 1038 (1977). But see United States v. Tobias, 836 F.2d 449, 451 (9th Cir.), cert. denied, 485 U.S. 991 (1988). Nevertheless, for the reasons set forth below, the Criminal Division believes that it is inappropriate to bring a prosecution under 18 U.S.C. § 641 when: (1) the subject of the theft is intangible property, i.e., government information owned by, or under the care, custody, or control of the United States; (2) the defendant obtained or used the property primarily for the purpose of disseminating it to the public; and (3) the property was not obtained as a result of wiretapping, (18 U.S.C. § 2511) interception of correspondence (18 U.S.C. §§ 1702, 1708), criminal entry, or criminal or civil trespass.

https://www.justice.gov/archives/jm/criminal-resource-manual-1664-protection-government-property-theft-government-information