When is a government a police state?

When is a government a police state? The answer is not obvious because there is no clear dividing line between the two; rather, ‘a government’ and ‘a police state’ are two points on a continuum.

Every government asserts its authority through force or the threat of force -- that is, through laws imposed by police or other armed agents. At what point on the continuum does a government cease to be limited and become an Orwellian police state. To answer 'where' requires a definition of the points. 

Do you feel threatened by your government? There's probably little reason to fear if you get all the permits, pay all the taxes, and follow all the rules they impose.