Constance Baker Motley—the visionary civil-rights lawyer, politician, and judge—helped transform American society over the course of her six decades in public life. When I started writing my new book about her, Civil Rights Queen: Constance Baker Motley and the Struggle for Equality, there was no question that I should explore the role for which she is best known: writing the original complaint in Brown v. Board of Education.

In that 1954 case, the U.S. Supreme Court ruled state-mandated school segregation to be unconstitutional. In a long list of more than a dozen attorneys whose names appeared on the briefs filed by the Thurgood Marshall–led legal team that won the landmark victory, Motley’s name stood out: she was the only woman in the illustrious, history-making group.

So Motley was the only woman on the legal team, but how much did gender really matter in her work life? As it turns out, a lot. I soon discovered a fact completely ignored by other writers: Motley helped litigate Brown v. Board of Education as a new mother.

Her baby’s first two years of life coincided with the relentless work and “excruciating pressure” of the civil-rights lawyers working to overturn segregation. “The staff put in shifts of fifteen to twenty hours a day, seven days a week, without requesting extra pay,” a N.A.A.C.P press release explained. The extraordinary workload sometimes required the lawyers to spend days away from their families and with little sleep.

In a long list of more than a dozen attorneys, Motley’s name stood out: she was the only woman.

Motley, who was 25 and in her second year of law school when she joined Marshall’s legal team as a clerk, began her career in civil-rights law after graduating from college, in 1946.

She wrote legal briefs and did the “nightmare” work, as she described it once, of proofreading briefs while facing the new pleasures and pressures of parenthood. She was both a sleep-deprived mother managing the tangle of emotions that beset working parents, and the only female attorney in a male-dominated workplace.

It was especially difficult to reconcile the roles of mother and lawyer given that it was the 1950s, an era in which women were expected to stay home while their husbands worked. (Motley’s husband also had a full-time job.)

Today, the causes Motley fought for, at home and in the courtroom, have made great strides. But they still have a ways to go.

Tomiko Brown-Nagin is a professor of constitutional law at Harvard Law School, a professor of history at Harvard University, and the author of several books. Her latest, Civil Rights Queen: Constance Baker Motley and the Struggle for Equality, is out now from Pantheon