This series documents the ACLU's considerable correspondence with the three branches of the federal government over the years, especially in the area of due process. Matters addressed with some frequency include rights of aliens, loyalty investigations, civil service questions, congressional investigations, military investigations, labor disputes, fair employment practices, Japanese-American internment, Indian affairs, and civil rights. In general the material is organized by department, although there are many subject files in this series. Since the ACLU did not consistently organize this material, the researcher is urged to review the entire list of subjects.

In its early years the ACLU shied away from lobbying for specific legislation, other than in the areas of amnesty for conscientious objectors and repeal of the wartime espionage and sedition acts. With the coming of the New Deal, the ACLU was much more involved on the legislative front, although the organization still did not have a Washington office at the end of Baldwin's tenure in 1950. The ACLU described legislation in a variety of ways: by author, by subject, by bill number and by the general name of the bill. Researchers are advised to read the list with care since there is no grouping of records; this is simply an alphabetical listing. Frequent topics include wiretapping, immigration and naturalization, labor, conscientious objection, civil rights, censorship, radio, and the espionage act.