The attorneys said Saturday that they sent letters to Lifetime warning that they would go to court in an effort to sequester the film if it isn't canceled. They also want a trailer removed from the network's website.
"Amanda Knox: Murder on Trial in Italy," is due to air Feb. 21.
Knox and ex-boyfriend Raffaele Sollecito were convicted in 2009 of sexually assaulting and murdering Meredith Kercher and sentenced to 26 and 25 years, respectively. Both deny wrongdoing and are appealing.