File - In this April 1, 2018 file photo, people attend a vigil for victims and survivors of a mass shooting in Las Vegas. The unprecedented move from MGM Resorts International to sue hundreds of victims of last year's mass shooting in Las Vegas using an obscure law never before tested in court has been framed by the casino-operator as an effort to avoid years of costly litigation, but the legal maneuver may not play out that way. (AP Photo/John Locher, File)