Professor Steven Horwitz explains here why he maintains that the US has become a police state. Liberal and conservative politicians alike have approved a vast expansion of the criminal law, and law enforcement officials routinely now use invasive, militaristic tactics that you’d have expected only in totalitarian countries. Horwitz provides some good examples. If you want many more, read Three Felonies a Day by Harvey Silverglate and One Nation Under Arrest, edited by Paul Rosenzweig and Brian Walsh.