In 2009, Paula Petrella sued United Artists and Metro-Goldwin-Mayer for alleged copyright infringement based on her late father Frank Petrella’s rights in the screenplay for the hit movie “Raging Bull,” which continued making money decades after its 1980 release. Because of the lengthy delay, the defendants countered with a motion to dismiss based on the equitable defense of laches — although Petrella’s request for compensation was limited to the three-year look-back period set by 17 U.S.C …