Screening Series: ‘The Judge’: Don’t touch Robert Duvall’s food. Please.

When director David Dobkin makes a movie, ideally he likes to put his cast through three weeks of rehearsal beforehand to work on the script, improvise and suss out back stories.

With the courtroom and family drama “The Judge,” which stars Robert Downey Jr. and Robert Duvall as an estranged father and son, Dobkin didn’t really have that option. Turns out Duvall doesn’t particularly like to rehearse, preferring to find out what happens the moment the director calls for the camera to roll.

And Downey, in Dobkin’s words, is a “movie star who’s never available.”

“By design,” Downey cracked at the Envelope Screening Series presentation of “The Judge.”

And Billy Bob Thornton rehearse? Forget about it. But despite their different outlooks, Dobkin did corral his actors for a few weeks of run-throughs.

In the video clip above, Downey, Duvall, Dobkin and producer Susan Downey talk about those sessions and what happens when, during an improv, an actor dares to eat off Duvall’s plate.

For more clips from “The Judge” screening — in which the group discusses the four-hour version of the film, and the increased pressure of being an actor-producer — check back here often.