"A man's home is his castle," the old English saying goes.

Since the American Revolution, Americans' homes have been considered sanctified space. Under the Castle Doctrine, first expressed in English common law, a person's home — whether it's a shack or a McMansion — is a protected space that no one can breach without the consent of the owner or, when it comes to the state, a lawful reason backed up by a judicial warrant. The tradition also says the agents must knock and announce their presence to let the homeowner know why there are strangers at his door. The rationale behind this was clear: avoiding unnecessary violence. When those conditions are not met, the homeowner has the right to use force to defend his property. Belief in the Castle Doctrine was so strong that it was enshrined in the Fourth Amendment, which prohibits government agents from conducting unreasonable searches and seizures against anyone's "persons, houses, papers, and effects."

Fast forward a little more than 200 years. The Castle Doctrine has been under sustained assault by police and politicians for decades. Consider this: "Today in America SWAT teams violently smash into private homes more than one hundred times per day," writes Radley Balko in his deeply unsettling Rise of the Warrior Cop. "The vast majority of these raids are to enforce laws against consensual crimes."

Since the 1960s, argues Balko, police forces inside the United States have increasingly taken on the appearance and mentality of an occupying force in direct violation of their popular oath "to protect and serve." Arising in a time of domestic instability, and spurred on by rising crime rates and drug use, the militarization of the nation's police forces by federal, state, and local governments has led to police officers with the mentality of a soldier who increasingly sees breaking down doors as a first, not a last, resort.

Special weapons attack teams