The Smith-Mundt Act is found in Title 22 of the United States Code, which is the “consolidation and codification by subject matter of the general and permanent laws of the United States.” Title 22 covers Foreign Relations, specifically the activities of the State Department and other agencies of international affairs, such as the Peace Corps and development organizations. (The Defense Department is under Title 10. The DoD is not referenced in or covered by Title 22, on this point alone Smith-Mundt does not apply to DoD.)
To be more precise, Smith-Mundt is in Title 22, Chapter 18: United States Information and Educational Exchange Programs. Selected sections of Chapter 18 of the current Smith-Mundt Act, as amended, appear below with excerpts and a notation of whether the section was in the original 1948 legislation, or added or modified after 1948. As you browse the legislation, you may notice the legislation has never been fully updated to reflect a) the establishment of USIA in 1952 and b) the disestablishment of USIA and the separation of its functions into State and the BBG in 1999.
The Smith-Mundt Act of 1948, in its original form, may be found here: Public Law 80-402: The United States Information and Educational Exchange Act, also known as the Smith-Mundt Act (PDF).
§1437: Utilization of private agencies – “…shall be the duty of the Secretary to utilize, to the maximum extent practicable, the services and facilities of private agencies…It is the intent of Congress that the Secretary shall encourage participation in carrying out the purposes of this chapter by the maximum number of different private agencies in each field…” [Section 1005 of the original Smith-Mundt Act of 1948; it has not been changed]
§1431. Congressional declaration of objectives – “The Congress declares that the objectives of this chapter are to enable the Government of the United States to promote a better understanding of the United States in other countries, and to increase mutual understanding between the people of the United States and the people of other countries. … an information service to disseminate abroad information about the United States, its people, and policies promulgated by the Congress, the President, the Secretary of State and other responsible officials of Government having to do with matters affecting foreign affairs…” [Was Section 2 of the Smith-Mundt Act of 1948; amended in 1961 and several times after]
§1461 General authorization – “The Secretary is authorized, when he finds it appropriate, to provide for the preparation, and dissemination abroad, of information about the United States, its people, and its policies, through press, publications, radio, motion pictures, and other information media, and through information centers and instructors abroad. Subject to subsection (b) of this section, any such information (other than “Problems of Communism” and the “English Teaching Forum” which may be sold by the Government Printing Office) shall not be disseminated within the United States, its territories, or possessions, but, on request, shall be available in the English language at the Department of State, at all reasonable times following its release as information abroad, for examination only by representatives of United States press associations, newspapers, magazines, radio systems, and stations, and by research students and scholars, and, on request, shall be made available for examination only to Members of Congress. … The Director of the United States Information Agency shall make available to the Archivist of the United States, for domestic distribution, motion pictures, films, videotapes, and other material prepared for dissemination abroad 12 years after the initial dissemination of the material abroad or, in the case of such material not disseminated abroad, 12 years after the preparation of the material. [Was Section 501 of the original Smith-Mundt Act of 1948; amended in 1972, 1979, and 1990]
§1461–1a. Ban on domestic activities by United States Information Agency – Except as provided in section 1461 of this title and this section, no funds authorized to be appropriated to the United States Information Agency shall be used to influence public opinion in the United States, and no program material prepared by the United States Information Agency shall be distributed within the United States. This section shall not apply to programs carried out pursuant to the Mutual Educational and Cultural Exchange Act of 1961 (22 U.S.C. 2451 et seq.). The provisions of this section shall not prohibit the United States Information Agency from responding to inquiries from members of the public about its operations, policies, or programs. [Inserted 1985, this is the "Zorinsky Amendment," modified in 1994.]
§1462. Policies governing information activities – “In authorizing international information activities under this chapter, it is the sense of the Congress (1) that the Secretary shall reduce such Government information activities whenever corresponding private information dissemination is found to be adequate; (2) that nothing in this chapter shall be construed to give the Department a monopoly in the production or sponsorship on the air of short-wave broadcasting programs, or a monopoly in any other medium of information.” [Section 502 in the original Smith-Mundt Act of 1948; not changed]
§1469. United States Advisory Commission on Public Diplomacy – “There is established an advisory commission to be known as the United States Advisory Commission on Public Diplomacy. …” [Section 604 in the original Smith-Mundt Act of 1948; amended several times, including in 1999 when the Commission was reduced with a staffing cap of 2 and a 50% budget reduction]
The following section of the Smith-Mundt Act of 1948 was removed in 1979 [it was previously 22 USC 1434]:
§1001 Loyalty Check on Personnel – No citizen or resident of the United States, whether or not now in the employ of the Government, may be employed or assigned to duties by the government under this Act until such individual has been investigated by the Federal Bureau of Investigation and a report thereon has been made to the Secretary of State: Provided, however, That any present employee of the Government, pending the report as to such employee by the Federal Bureau of Investigation, may be employed or assigned to duties under this Act for the period of six months from the date of its enactment. This section shall not apply in the case of any officer appointed by the President by and with the advice and consent of the Senate.