Wikipedia calls a police state one "in which the government exercises rigid and repressive controls over the social, economic, and political life of the population."
Merrian-Webster's definition is "a political unit characterized by repressive governmental control of political, economic, and social life usually by an arbitrary exercise of power by police and especially secret police in place of regular operation of administrative and judicial organs of the government according to publicly known legal procedures."
The Oxford dictionary calls it "a totalitarian state controlled by a political police force that secretly supervises the citizens’ activities."
Post-9/11, America enacted a disturbing array of police state laws. National and Homeland Security Presidential Directives supplement them.
So do secret memos and memoranda, as well as executive orders and other presidential diktats. George Bush called the Constitution "just a goddamn piece of paper."