first association with the company. In 1919, while still a law student, he had helped draft the company's articles of incorporation. Dickerson considered his work with Supreme Liberty Life Insurance to be his most outstanding contribution to American society. While working for Supreme Liberty Life Insurance, Dickerson opened a law office and shared office space with fellow University of Chicago Law graduate Wendell E. Green, who later became a Circuit Court judge. In 1923, Dickerson joined a partnership with Edward H. Morris and James B. Cashin to form Morris, Cashin, and Dickerson. Concurrent with this partnership, Dickerson served as an assistant corporation counsel for the city of Chicago. In 1927, Dickerson was instrumental in establishing Burr Oak Cemetery, one of the few African American cemeteries in southwestern Cook County. Later, during the Great Depression, Dickerson helped persuade Supreme Liberty Life Insurance to step in and save the cemetery after Burr Oak defaulted on its mortgage. Dickerson was known as "the dean of Chicago’s Black lawyers," and in 1933 became the first African American appointed as Illinois Assistant Attorney General under Governor Henry Horner. Dickerson served in that role until 1939. Famously, Dickerson successfully argued before the U. S. Supreme Court in the landmark Hansberry v. Lee case. Hansberry involved a Chicago home purchased by real estate broker Carl Augustus Hansberry in a neighborhood with a racially restrictive covenant. Racially restrictive covenants were used to restrict black residents from living in certain neighborhoods (in turn creating a Black Belt of crowded, dilapidated, and under-resourced neighborhoods for black residents). Hansberry purchased a house in Woodlawn, which was under a racially restrictive covenant, with money borrowed from the Supreme Liberty Life Insurance Company. Hansberry served on the board of the Chicago NAACP with Dickerson and was the father of playwright Lorraine Hansberry. The events giving rise to Hansberry v. Lee inspired Lorraine Hansberry's play A Raisin in the Sun. Dickerson determined that there was a better chance to win the case based on a procedural issue surrounding class suits rather than argue the constitutionality of racially restrictive covenants. The decision in Hansberry v. Lee ended a racially restrictive covenant on the South Side of Chicago and paved the way for the Supreme Court to declare to racially restrictive covenants unconstitutional in Shelley v. Kraemer and Sipes v. McGhee in 1948. Dickerson joined the Cook County Bar Association in 1920 and was elected as