As a producer on Kenneth Lonergan’s Manchester By the Sea, Matt Damon had push-comes-to-shove final cut approval over the film–a safeguard against the legal and reputation-staining legacy still attached to Lonergan over his troubled 2011 film Margaret.

“It was just a way of keeping everyone calm,” Damon said, appearing via Skype at a Produced By panel about the making of Manchester By the Sea, due out next month and which is already being talked about as an Oscar candidate.” “If stuff got out of control, I would come in and very rationally and calmly help out.”

As it happened, Damon didn’t need to exercise final approval over Manchester, which was among the most sought-after films at this year’s Sundance Film Festival, with Amazon and Roadside Attractions buying up distribution rights.

Damon praised Kimberly Steward and her company K Period for being willing to bankroll a Lonergan film when no one else would. “It was not an easy decision. If it was, we would have had a lot of people jockeying to make the movie. We had nobody except K Period.”

This was due, Damon said, to Lonergan’s reputation: “Kenny’s in a certain place now that he really wasn’t then,” Damon said. “His reputation was really sullied.”

Finally released in 2011 without a marketing push and with some critics hailing it as a masterpiece, Margaret played out as Lonergan’s magnum opus that wasn’t, its legacy playing out in court with producer Daniel Gilbert arguing that Lonergan had failed to meet his obligations to deliver a releasable film on time, and Lonergan’s reps arguing that Gilbert had hijacked his art.

Manchester By the Sea stars Casey Affleck, Michelle Williams and Kyle Chandler. Damon said he initially developed the project as an uncle/nephew story with actor Jon Krasinski, then brought in Lonergan to write the script.

But Lonergan was “under water with Margaret at the time,” said Damon, who also had a role in that film (indeed, Damon joked that when he ran into Lonergan’s attorney at Sundance this year, they had last seen each other when Damon was deposed in the Margaret case.)

Damon’s involvement with Manchester morphed according to his own commitments and Lonergan’s growing interest in the project,

Joining Damon were the film’s five principal producers, including Kimberly Stewart, Lauren Beck, Chris Moore and Kevin Walsh. Moore, who produced Good Will Hunting for Damon and Ben Affleck, cautioned against optimism over the fact that an emotionally tough move like Manchester got made in today’s Hollywood climate. He calls Manchester an anomoly in a film business that’s otherwise “wildly in a moment of a bubble,” with money floating around for independently financed films but with a huge problem at the other end: no audience.

“In the next five years, we gotta figure out how to get people back out there to watch these movies,” he said.