MGM Resorts International has filed federal lawsuits against more than 1,000 Las Vegas mass shooting victims in an effort to avoid liability.  The company, which owns Mandalay Bay and the Route 91 Harvest festival venue, argues that it cannot be held liable for Oct. 1 deaths, injuries or other damages, adding that any claims against MGM parties “must be dismissed,” according to complaints filed Friday in Nevada and California...The company cites a 2002 federal act that extends liability protection to any company that uses “anti-terrorism” technology or services that can “help prevent and respond to mass violence.”...[T]he company argues, the security vendor MGM hired for Route 91, Contemporary Services Corp., was protected from liability because its services had been certified by the Department of Homeland Security for “protecting against and responding to acts of mass injury and destruction.”  The lawsuits argue that this protection also extends to MGM, since MGM hired the security company.  They...ask that a judge decide if the 2002 act is applicable, and if so, determine that future civil lawsuits against the company are not viable...