[mewzilla]

Lug, they have to have a warrant. So with a warrant in hand, why risk the cops and/or losing evidence by making like an Avon lady and knocking?

[green iguana]

why risk the cops

Indeed. Bursting into a house unannounced is much riskier for the cop than knocking and letting a person calmly answer the door.

[lugsoul]

Um, you may not understand this, but the risk to the cops is far greater if they kick in the door without knocking.

As far as the risk to evidence, I believe that there has been quite enough violence done to the 4th Amendment in the name of the War on (some) Drugs. It needs to end.