Aaron Sorkin was ''scared'' about directing 'The Trial of the Chicago 7' due to the calibre of the cast.

The 59-year-old screenwriter is helming just his second film and admits he was daunted at the thought of working with major screen stars on the Netflix project such as Yahya Abdul-Mateen II, Joseph Gordon-Levitt and Michael Keaton among others.

Aaron explained: ''It was scary directing 'Chicago 7'. I only have one movie under my belt, 'Molly's Game', which had three principal characters. This film has 11 stars, most of whom are leads in their own movies.''

The movie is based on the infamous 1969 trial of seven men charged by the federal government with conspiracy and inciting a riot, as a result of the counterculture protests in Chicago at the 1968 Democratic National Convention. Aaron admitted that he had no idea about the story when first approached for the project by Steven Spielberg back in 2006.

He recalled: ''When I left his house, I called my father because I didn't know about the events Steven was referring to.

''I said yes because it was Steven and he said there was a trial, so I thought courtroom and that was enough.''

The project has long been in development although Aaron believes that Donald Trump's election as US President and racial tensions in the country has made the movie as relevant as ever.

Speaking at the San Sebastian Film Festival, the Oscar-winning screenwriter said: ''Spielberg saw 'Molly's Game' and was sufficiently pleased to suggest I direct 'Chicago 7' and Trump was elected.

''At his rallies, Trump started being nostalgic about the good old days beating up protestors and the movie became relevant again.

''At that time, I had no idea how relevant it would come with the deaths of George Floyd, Ahmaud Arbery and Breonna Taylor.''