Kevin Bacon, Chris Colfer and John C. Reilly have joined the cast of the Los Angeles premiere of the play 8.

8, which was written by Milk screenwriter Dustin Lance Black, is based on the trial over the constitutionality of California's gay marriage ban, Proposition 8.

The 13-day trial held last year in San Francisco resulted in federal Judge Vaughn Walker, now retired, declaring the ban unconstitutional. A federal appeals court earlier this month upheld Walker's ruling.

“People need to witness what happened in the Proposition 8 trial, if for no other reason than to see inequality and discrimination unequivocally rejected in a court of law where truth and facts matter,” said Black in a statement. “I've built my career around exposing and uncovering 'the real story.' The goal of 8 is to show the world that marriage equality is a basic constitutional right and that those who would deny this basic freedom from loving, committed couples have only vitriol and baseless hyperbole to fall back on. The facts are on our side and truth always finds the light. We are doing all we can to help speed that process along.”

The Broadway premiere of the play raised over $1 million for the American Foundation for Equal Rights (AFER), the group formed specifically to challenge Proposition 8.

The March 3 Los Angeles premiere of 8 will feature George Clooney and Martin Sheen playing plaintiffs' co-counsel David Boies and Theodore B. Olson, respectively. Maggie Gallagher, co-founder and former chairman of the National Organization for Marriage (NOM), will be played by Glee co-star Jane Lynch.

(Related: George Clooney calls gay marriage a civil right.)

John C. Reilly will play Judge Walker. Kevin Bacon will take on the role of Charles J. Cooper, the lead attorney for the proponents of Proposition 8, while Chris Colfer will play Ryan Kendall, a young man who testified about his experience being sent by his parents to so-called “reparative therapy” as a teenager.