During a campaign to exonerate the Scottsboro Boys—a group of imprisoned black Alabama youth in danger of being lynched—the local chapter of the National Negro Congress (NNC) held its first mass meeting in DC at Metropolitan Baptist Church (then at 13th and R streets NW) in 1936. At this meeting, NNC founder John P. Davis called for the group to address police brutality, so-called "urban lynching," in the nation's capital. Later that year, a Civilian Conservation Corps worker at the National Arboretum became "the fortieth colored person shot to death by Metropolitan police since 1925," reported the Afro-American, which also noted that "every officer involved has been exonerated." The NNC quickly ramped up its DC campaign, joining the newspaper, the NAACP, the Washington Bar Association and others in a coalition to demand that Congress investigate the "unnecessary and unlawful use of force" by District police. The radio station WOL broadcasted weekly on the topic.
Calling itself the Joint Committee for Civil Rights in the District of Columbia (and later the Citizens Committee Against Police Brutality), the coalition held a mock trial against "killer cops" in May 1937 at John Wesley AME Zion Church, 14th and Corcoran streets NW. George E.C. Hayes acted as a prosecuting attorney and Lucy Diggs Slowe, Howard University Dean of Women, served as a mock judge. The trial brought attention to a large public audience the District's abusive treatment of its black citizens.
After a series of violent episodes in the winter of 1937-38—a Howard student was beaten and a young man fleeing a traffic accident was fatally shot—the NNC-led coalition held mass meetings in the summer of 1938 at Lincoln Temple Congregational Church and at Vermont Avenue Baptist Church, where Charles Hamilton Houston called for voting rights as a prerequisite for ending police terror in the District. That July, for the first time, an officer was indicted but was ultimately acquitted for fatally shooting a mentally ill veteran. The NNC continued to help organize protests and demand accountability, eventually gaining establishment of a civilian review board.
In contrast to more conservative allies such as the NAACP, the NNC promoted direct action. Its pickets at a federal agency charged with ensuring that African Americans were hired for war-related jobs led the Glenn Martin aircraft factory, near Baltimore, to integrate its workforce, and ultimately to employ 5,000 black workers.
The local NNC also worked to desegregate federally operated parks and sports facilities, including the Washington Tourist Camp, which was open to whites only until April 1940. A 1939 report documenting segregated and prohibitively expensive recreation sites was produced by the NNC's Thelma Dale, who also co-led a campaign to end discriminatory hiring practices by Capital Transit, which operated DC's streetcars.
During the 1930s, the NNC Headquarters were located at 717 Florida Avenue NW.