Realizing that she wanted to have the real life Ruth Bader Ginsburg appear at the end of her film, director Mimi Leder wrote to the Supreme Justice and was delighted when she responded with a yes. Her appearance in the film took three takes (Ginsberg wouldn't allow any more).
Backers of the film insisted that Ruth Bader Ginsburg's husband, played in the film by Armie Hammer, should not appear so supportive and be more antagonistic towards his wife's success. Screenwriter Daniel Stiepleman refused to do this.
When Ruth Bader Ginsburg is preparing to appear in front of the federal appeals court, she practices in front of a panel of mock judges, including her former professor Gerald Gunther and the legal scholar, civil rights activist, and pioneering Episcopal priest Pauli Murray. During the practice session, Murray assumes the identity of a male judge; in Rosalind Rosenberg's 2017 biography "Jane Crow: The Life of Pauli Murray," Rosenberg reveals that Murray was, in fact, what we would today characterize as transgender--he identified as male.