There is some doubt as to what exactly constitutes a "Police State."
There are classic examples: Nazi Germany, the communist regimes of Eastern Europe in the Cold War. The USSR. The PRC under Mao. Haiti under Papa Doc. And many others, I am sure. I hope I didn't leave out your favorite. If I did, please post it with the reasoning of why it was or is a Police State.
The paranoid among us(I am one

) sense that a Police State is possibly an imminent threat in America. If you think that this is likely, please say why. Same token, you who think the chance is remote that America could shift into the Police State mode: say why.
What are the characteristics that identify a Police/Security State? How does a Police State work? What are the strengths and weaknesses? What could bring about the demise of a Police State?