Executives at the parent company of their label Virgin Music sued the band in 2008 for $30 million (£18.75 million), claiming the stars failed to produce an agreed number of albums.
Frontman Jared Leto and his bandmates fought back against the industry chiefs - and the case was eventually settled in 2009.
Now Leto wants to tell his side of the story with a film, according to music industry expert Bob Lefsetz.
In a post on his blog, Lefsetz writes, "He's (Leto) making a movie about 30 Seconds To Mars and its fight with EMI in the wake of the Terra Firma takeover. They were bugging me eons ago, but then faded away, I saw the album came out (sic), I figured the film was shelved. But then Jared himself tracked me down, said it was still on and would I come on camera and testify."
Bosses at private equity firm Terra Firma purchased EMI for £4.2 billion in 2007.