One night a few years ago, as George Stevens Jr. sat down to dinner with Sidney Poitier, the iconic actor made an announcement: He wanted to return to Broadway.

“I haven’t been on the stage in 40 years. I want to go back on the stage,” Stevens recalls Poitier saying. At that, Stevens thought to himself: “I’ll write a play on Thurgood Marshall.”

It was a familiar role for both men; Poitier played the Supreme Court justice as a young lawyer arguing against school segregation in the Emmy Award-winning 1991 television series “Separate but Equal,” which Stevens wrote and produced.

But as the play came together, Stevens said, Poitier had a change of heart. At age 75, the legend of stage and screen feared he wasn’t up to carrying a one-man show.

So Stevens reached out to a comparably decorated actor, Laurence Fishburne, a casting decision that soon drew a 2008 Tony nomination for Fishburne’s Broadway portrayal of the eponymous character in “Thurgood.”

“He’s a superb actor,” Stevens said of Fishburne, 48. “And he’s younger than we might have thought of casting it, which brings a kind of vitality to it.”

The play’s first off-Broadway production opens tonight at the Kennedy Center, not far from the building in which Marshall famously argued Brown v. Board of Education as a young lawyer for the National Association for the Advancement of Colored People.

A retired Marshall drives the narrative, reflecting in a fictional lecture to students at Howard University School of Law on his life and career as a trailblazing attorney and, ultimately, the first black Supreme Court justice.

Along the way, Fishburne shifts between the old and the young Marshall, mixing in other characters who shaped the American icon’s life.

Born in Baltimore and educated at Howard, Marshall casts a large shadow in Washington, D.C.; he’s a hero and pioneer in the legal field. But Stevens said he thinks that on a broader scale, Marshall is underappreciated for his role in the civil rights movement.

“Not many people know of the years and years of important court cases, desegregating grade schools, public accommodations and, finally, the children’s schools,” Stevens said. “Politically, he’s the most significant figure in race relations in this country. What Thurgood did made possible what Martin Luther King Jr. did.”

But for all his passion for the story, Stevens insisted he’s not in it to proselytize.

“It’s a slippery slope if you write a play, or make a film even, with the purpose that you’re going to change the way people think,” he said. “My agenda was simply exploring the life and the career and the humanity of Thurgood Marshall.”

The production features no shortage of verbatim quotes, making it part play, part history lesson.

The challenge for him as a first-time playwright, Stevens said, was organizing the material to make it compelling, and not just a lofty dissertation.

Stevens said he drew inspiration from David Rintels’ 1975 one-man show, “Clarence Darrow,” in which Henry Fonda played the famous lawyer who argued the 1925 Scopes Monkey Trial. It showed him that courtroom theatrics could be equally entertaining on a different stage.

But the feat was also made easier by Marshall’s own “extraordinary sense of humor,” Stevens said.

“It’s often applied to the kinds of experiences he had, and he saw them with an irony that I guess made them survivable,” he said. “People come to the play knowing that it’s going to be good for them, but they’re really surprised by how funny it is.”

The theatrical production appropriately has several political ties. Former Clinton adviser Vernon Jordan produced it, and Stevens said he’s expecting several Members and justices in the audience on opening night, although he wouldn’t say which ones.

And he said he got a little promotional help from the man he supported in the 2008 Democratic primary.

“The president stepped in and nominated one of Marshall’s former law clerks to the Supreme Court to enhance our publicity,” Stevens joked, referencing Elena Kagan.

Marshall’s is the only portrait that hangs in President Barack Obama’s White House office. So Stevens said he expects the president will come to one of the shows, especially since he missed the Broadway run.

“I got a message on my voice mail one day, and it said, ‘I know that your play is opening tonight and I wish you great success. I think that if I wasn’t running for president, I’d be there,'” Stevens said.

Though he’s quite busy these days, too, the president will have several chances to see the show. The 90-minute play runs nightly Tuesday to Sunday with afternoon productions on the weekends through June 20.

Tickets are available at kennedy-center.org.