A SWAT team blew a hole in my 2-year-old son
This was the result of a no-knock warrant: http://en.wikipedia.org/wiki/No-knock_warrant, which allows police to enter a home without prior warning, on the theory that giving notice will allow people inside to destroy evidence. They are almost uniquely a product of the drug war. One can imagine very few situations outside of drugs were evidence could be so easily destroyed as to justify a no-knock warrant.