The film, On the Basis of Sex, focuses on Ginsburg's life as she fights for equal opportunities in her career.
Daniel Stiepleman wrote the script, Robert Cort (Save the Last Dance and Runaway Bride) is producing and Ram Bergman (Star Wars: Episodes VIII and IX, and Looper) is executive producing, Deadline reported.
Marielle Heller (The Diary of a Teenage Girl) is in talks to direct and Focus Features is likely to finance.
It's possible the movie could have a production start date before the end of the year.
Portman is next set to appear in Terrence Malik's Knight of Cups with Christian Bale. She's also been rumored to star in sci-fi film Annihilation based on the novel of the same name by Jeff VanderMeer.