The US federal and state governments have vastly overreached and abused their powers, and our justice system is severely dysfunctional. In general, people in this country are NOT free, especially the poor and minorities who are oppressed. The legislature, law enforcement and various “security” agencies all make up and maintain the machinery that carries out and keeps this oppressive system in place.
That said, by the definitions given in this thread and by my own understanding of the word, the US is NOT a police state. It is also still more free and less oppressive than almost any other country on earth and than any other time period, even in our own history. But we need to keep the pressure on, because there is still a lot of work to do.
When libertarians on slashdot use the term “police state”, they are mostly referring to the appalling lack of transparency in our government in addition to the massive and systematic spying that “intelligence” agencies perpetrate on our own citizens. Not to mention the minor-in-scale-but-massive-in-consequences imprisonment and torture without trial of suspected terrorists at Gitmo. And in those respects only, the US is disturbingly similar to both real totalitarian regimes like Stalin’s, and fictional oppressors like Big Brother.