Julius J. Epstein, the screenwriter and playwright who co-wrote Casablanca and the penned the libretto for Stephen Sondheim's early-career musical, Saturday Night, died Dec. 30, according to wire reports.

Mr. Epstein was 91. His frequent collaborator was his twin brother, Philip, who won an Academy Award, along with Howard Koch, for 1942's film classic, "Casablanca." The picture was based on an obscure play, Everybody Comes to Rick's. Philip Epstein died in 1952.

The brothers wrote a play about youthful romance in Depression-era Brooklyn, Front Porch in Flatbush, which, in the mid-1950s, was to be turned into a musical called Saturday Night, with songs by a youthful composer lyricist Stephen Sondheim. The death of producer Lemuel Ayers scotched the project, but it was revived in the late 1990s in England and further tweaked by Sondheim for a Chicago tryout (by non Equity Pegasus Players) and a 1999-2000 New York debut at Second Stage Off Broadway. Mr. Epstein got sole libretto credit in the 2000 New York Playbill.

The New York City native, born in 1909 to a livery stable proprietor, collaborated with his brother on the plays And Stars Remain (1936), Rufus and His Wife (1941), Chicken Every Sunday (1944) and a tryout, That's the Ticket (1948), which closed out of town at the Shubert in Philadelphia.

Among screenplays co-written with his brother are "Stars Over Broadway," "The Man Who Came to Dinner," "Mr. Skeffington" and "Arsenic and Old Lace." Alone, he wrote the screenplays to "The Last Time I Saw Paris," "Young at Heart" and "The Tender Trap." With Louis Peterson, he wrote screenplays for "A Light in the Piazza" and "Take a Giant Step." According to Reuters, when the U.S. government was rooting out alleged communists in the entertainment industry during the 1940s and 1950s, Epstein was asked if he belonged to a subversive organization.

He answered, "Yes — Warner Bros.''

— By Kenneth Jones