Back in the "good old days" police could do pretty much anything they wanted and be found in the right. Even dangerous acts based on false allegations in warrant affidavits. Not anymore. Officers who want to survive for a career have to use a lot more common sense than the previous generations. Why's that, you ask? One part of the answer is culture change and the legal and political climate. What makes no-knock warrants so dangerous today is that home invasions used to be virtually non-existent