The Prop 8 trial now has its cast.

On Sept. 19 at the Eugene O’Neill Theatre in New York, performers will do a staged reading of “8,” a new work from Dustin Lance Black based on the January, 2010, trial, after which U.S. District Judge Vaughn Walker found that California’s ban on same-sex marriage was unconstitutional.

Bob Balaban will play Walker; Morgan Freeman and John Lithgow will play David Boies and Ted Olson, the legal duo challenging Prop 8; Bradley Whitford will play Charles Cooper, the lead attorney representing the defenders of the initiative; and Matt Bomer and Cheyenne Jackson will play Jeff Zarrillo and Paul Katami, one of the same-sex couples who are plaintiffs in the case.

Also in the cast: Christine Lahti and Marisa Tomei as the other plaintiffs, Sandy Stier and Kris Perry, and, as trial witnesses, Anthony Edwards, Larry Kramer, Rory O’Malley, Rob Reiner and Yeardley Smith. Campbell Brown will play the role of a broadcast journalist.

The staging will be a benefit for the American Foundation for Equal Rights, which has been challenging Prop 8. Black and Reiner are among the members of its board of directors.

The irony in the staging is that Olson, Boies and the rest of their legal team are pushing for the release of tapes of the actual trial, which was shot by videocam but never broadcast.

Joe Mantello will direct the reading.