The USA (and maybe other countries) seem to think that police states are only police states if the police are consciously, actively, only interested in evil. Most of those creating and maintaining police states are not evil. They are just doing what they can within the system. The individual actions make sense to someone trying to do good. They just neglect liberty a bit in order to get things done and then a bit more and then a bit more but don't see themselves as creating a new police state.
The USA constitution has fairly good protections in place. McCarthyism gives a extremely clear example of the dangers when those with power allow a few to abuse the system. And we have many more than a few abusing the system now.
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