Born in New Orleans in 1876, John Baptiste Hall, Jr. graduated from Wesleyan Academy before enrolling at Yale. He graduated from Sheffield in 1897, and then received his medical degree from the University of Pennsylvania in 1901. Hall married Harriet Curtis in 1906, and their son, John B. Hall III, was born the following year.
During World War I, Hall served as an assistant medical examiner for the draft board. He did postgraduate work at Harvard and was active in the Congregational Church, serving as a deacon and treasurer. He worked as a medical examiner for the Massachusetts Savings Bank Life Insurance and for the Massachusetts Youth Service. Hall was the first Black doctor to intern at Boston City Hospital in 1931.
During World War II, Hall again worked as a medical examiner for the draft board, as well as deputy medical director for the Boston Civilian Defense Organization and as a substitute medical inspector for Boston Schools. He was appointed by the Massachusetts governor to the State Advisory Council to the Department of Public Health in the 1940s. This council approved the construction of hospitals and health centers and the licensing of hospitals in the state.
In March 1913, the Yale Alumni Weekly shared the news that Charles Howard Warren, father of late Yale student Lewis Baker Warren (Sheffield class of 1910), had offered $5,000 to fund a scholarship in memory of his son at the Sheffield Scientific School. However, one of the stipulations was “that the benefits of the Scholarship shall be confined to sons born of white, Christian parents, both of whom were born citizens of the United States.” The following month, a letter from John B. Hall, Jr. was printed in the Yale Alumni Weekly calling on the school to reject the offer due to the discriminatory terms. Referencing members of the international “Cosmopolitan Club” pictured in the Yale Alumni Weekly, he wrote:
The thought that my son and the sons of these future sons of Yale might be discriminated against in the award of a scholarship because of certain restrictions imposed by the donor, notwithstanding their eligibility otherwise, has a tendency to cast a shadow, as it were, over the picture and to discourage, I firmly believe, many sons of Yale. [...] If the Corporation has not yet accepted this offer, I trust it will find a way to decline it and thus maintain the honor and spirit of Yale, which never has and never will offend its sons by discriminating against its grandsons.
Yale accepted the endowment under the terms outlined by Warren, and received an additional $1,000,000 for the scholarship fund when Charles Howard Warren died.
In 1915, after the release of the racist film The Birth of a Nation and the national protests that ensued, Hall testified in support of a state bill that would transfer censorship of films from local mayors and licensing boards to the State Board of Labor and Industries. The effort was covered by the Boston Globe.
Following a heart attack in 1948, Hall entered partial retirement. He died in 1959 in Chicago.