At some point, an enthusiastic squad will crash through a door of a well armed and experienced veteran who has committed no crime. He will kill several police officers under the belief that they are home invaders.
He will be tried and acquitted of multiple counts of murder, even if tried several times.
Only then will the message *start* to get through the thick skulls that this is not an appropriate use of police power, except in extraordinary circumstances. But many instances of this kind, perhaps ending up with dozens of dead officers and innocent homeowners, before policies are changed.
Someone who is a criminal may actually rig a site so that it is a death trap capable of killing many officers, but even they might do it in such a way that it appears to be accidental. Say be creating a weak floor over a basement full of carbon dioxide gas, generated by a “defective” piece of equipment. Once the floor collapses, the officers would suffocate in a few seconds, before they could climb out.
A criminal organization could systematically wipe out the drug squad of a police department, as they are doing in Mexico. It is almost a wonder that they haven’t tried to do so already.
If the drugs were inside, would it have been impossible for the police to send two detectives to knock on the door, show a warrant and go inside?
A drug house surrounded with pit bulls, barbed wire, and known to have several armed residents with long prison records in residence, is one thing.
But a suburban couple with no record is another (i.e., no need to use the SWAT squad; their most likely form of resistance will be to call a lawyer).