I'm into the abolishing of this myself. It will only lead to both the police and occupant getting injured or at the very least, very pissed off enough to sue the district of (wherever) for invasion of home privacy, etc... it's a very legal-tangled road. Plus, if they're that concerned about people destroying evidence, they should already have someone covering all possible escape routes, and then just ahead and knock and enter after that. You could catch them in the act, thus red handed guilty. Or if they try to run, you have it covered.
This method is horrible for both parties involved.