The widow of a judge who died of lung cancer last year can sue Blue Cross for refusing to tell him about his right to seek an experimental treatment that his doctor said was his only hope, a California appeals court has ruled. The decision is the first to allow policyholders to seek damages from claims administrators, who advise insurers on coverage for millions of Californians. Blue Cross is the main administrator for CalPERS, the California Public Employees' Retirement System, which insures 1.6 million state and local government employees and retirees.