The studio has acquired the life rights of Jim Obergefell, the lead plaintiff in the lawsuit that went to the court.
It has also bought life rights to Obergefell's attorney Al Gerhardstein.
The Fox 2000 division has set up the project with producers Wyck Godfrey and Marty Bowen through their Temple Hill banner, whose credits include the five "Twilight" films and "The Fault in Our Stars".
The studio has also bought the movie rights to a book proposal by Obergefell and journalist Debbie Cenziper, to be titled "21 Years to Midnight".
Obergefell married John Arthur in Maryland in 2013, three months before Arthur died. The state of Ohio refused to list Obergefell as his spouse on the death certificate, so Obergefell sued.