"Justified" producers are under fire from an artist who claims they ripped off one of his paintings for their promotional art ... and now, he's demanding they ditch the ads -- OR ELSE.
Attorney Keith Davidson fired off a cease and desist letter on behalf of artist Gabe Leonard ... accusing FX Networks -- which produces the hit show -- of copying his original piece "Double Fist" in its ads for the new season.
The letter cites several similarities -- rugged U.S. Marshals, pistols drawn, hats tipped, color schemes -- and concludes its a clear case of copyright infringement.
FX says "no comment"-- but we gotta ask ...