Congratulations Dirty, you completely missed the point. You keep bringing up ancillary stuff that I NEVER mentioned in my recent post. Emergencies: CHECK! The problem with that, though, is who decides what constitutes an emergency? Beating the snot out of a child: emergency. Every house BUT MINE on the block are in rubble... not an emergency.
We're dealing with extremes, and then I'm getting lambasted by granularity. You're completely missing the point.
The only ones who possibly can decide that, at the moment it is occuring, are the police. And we trust them to do that correctly because no other option is possible.
The "check" on that is that the "on the spot" decision to use force for an unannounced entry is subject to later review by the courts. And if the police are wrong, they may well get sued or otherwise smacked around by the courts. They naturally want to avoid that, so there's your "check". I mean, why in the world would the police want to blast down the doors of random citizens who've done nothing wrong? There's no possible motivation for them to take the time and energy to do that just for kicks.
The only time they're going to do that is when they have a reasonable, good-faith belief that immediate, unannounced entry is imperative. And we want them to have the ability to do that to prevent the rape/murder/child abuse situation that doesn't leave time to get a warrant or to knock first politely.