Oakland's Grand Lake Theatre decided to allow customers of all ages to view Michael Moore's documentary "Fahrenheit 11/9" and promoted the decision via its marquee, gaining approval from the filmmaker himself.

Moore's film explores American politics and the country's social climate following the election of Donald Trump, while looking into gun violence and the water crisis in Flint, Mich.

Grand Lake Theatre owner Allen Michaan took a stance against the movie's R-rating and will allow theatergoers of all ages into the film — much as he did with another Moore documentary, "Fahrenheit 9/11" in 2004.

"We will not enforce the R Rating on Fahrenheit 11-9!" the marquee on the Grand Lake states. "Political discourse must not be stifled."

Moore shared a photo of the movie theater and its marquee message Sunday via social media, and echoed the sentiment, thanking the theater for its gesture.

"Thank you Grand Lake Theater in Oakland, CA for not enforcing the R rating on my film and allowing tweens and teens in to see it," Moore wrote. "'Political Discourse Must Not Be Stifled'. We all agree!"

Michaan, for his part, doesn't take his defiance of the Motion Picture Association of America's rating lightly. He told SFGATE that while he agrees with R ratings for films that contain extreme violence or sex, he felt that the extreme rating for Moore's latest film, "reeks of political censorship."

"My feeling is that it is wrong for the MPAA to put an R rating on a film that is clearly not deserving of an R rating," Michaan said. "It is very important, especially in what is going on today politically with the young people — both in the MeToo movement and in the movement for sane gun laws, following the epidemic of school shootings that we've had and what happened in Florida — I think it is really, really wrong for any kind of attempt by censorship ... to keep young people out of political discourse."

"Yes, there are some scenes of gun victims that are graphic and upsetting," Michaan said, "but this is something that I'd rather young people saw up on the screen of a theater and become active in preventing from happening, rather than seeing [gun violence] in person at their school. I'm all for the political activism that comes from young people seeing a film like this."

The MPAA's R ratings are meant to serve as a warning regarding the contents of a movie, stating that those under 17 years of age should have an accompanying parent or guardian. Whether the ratings are enforced, however, is up to theater owners and following the MPAA's guidelines is not mandatory — the ratings are more of a guide for parents, not a rule or law.

Michaan dates his politically charged marquees on the Grand Lake as far back as 2000, during the Supreme Court's decision on the election recount, and it's something he vows to continue going into November's mid-term elections.

"I think that being the owner of the Grand Lake Theatre, I have the opportunity to do good, and to influence people and to help effect change," Michaan said. "I wish I could do more, but everyone has to do what they can do — so this is what I do, and will continue to do.

"...between now and the election, it's going to political comments full-time on that marquee. I know it costs me customers, I know Republicans won't come to my theater, but it's more important to be principled."

Read Dianne de Guzman's latest stories and send her news tips at ddeguzman@sfchronicle.com.

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