Police got a search warrant for Banks' (D) home. They arrived there, about 2 o'clock on a Wednesday afternoon, officers posted in front called out 'police search warrant' and rapped hard enough on the door to be heard by officers at the back door. After waiting for 15 to 20 seconds with no answer, the officers broke open the front door with a battering ram. D was in the shower and testified that he heard nothing until the crash of the door, which brought him out dripping to confront the police. The search produced weapons, crack cocaine, and other evidence of drug dealing. D moved to suppress evidence, arguing that the officers executing the search warrant waited an unreasonably short time before forcing entry, and so violated both the Fourth Amendment and 18 U. S. C. §3109.1 The District Court denied the motion. D pled guilty, reserving his right to challenge the search on appeal. A divided panel of the Ninth Circuit reversed and ordered suppression of the evidence found. The majority set out a nonexhaustive list of 'factors that an officer reasonably should consider' in deciding when to enter premises identified in a warrant, after knocking and announcing their presence but receiving no express acknowledgment: '(a) size of the residence; (b) location of the residence; (c) location of the officers in relation to the main living or sleeping areas of the residence; (d) time of day; (e) nature of the suspected offense; (f) evidence demonstrating the suspect's guilt; (g) suspect's prior convictions and, if any, the type of offense for which he was convicted; and (h) any other observations triggering the senses of the officers that reasonably would lead one to believe that immediate entry was necessary.' The majority also defined four categories of intrusion after knock and announcement, saying that the classification 'aids in the resolution of the essential question whether the entry made herein was reasonable under the circumstances': '(1) entries in which exigent circumstances exist and non-forcible entry is possible, permitting entry to be made simultaneously with or shortly after announcement; (2) entries in which exigent circumstances exist and forced entry by destruction of property is required, necessitating more specific inferences of exigency; (3) entries in which no exigent circumstances exist and non-forcible entry is possible, requiring an explicit refusal of admittance or a lapse of a significant amount of time; and (4) entries in which no exigent circumstances exist, and forced entry by destruction of property is required, mandating an explicit refusal of admittance or a lapse of an even more substantial amount of time.' The panel majority put the action of the officers here in the last category, on the understanding that they destroyed the door without hearing anything to suggest a refusal to admit even though sound traveled easily through the small apartment. The majority held the 15-to-20-second delay after knocking and announcing to be '[in]sufficient ... to satisfy the constitutional safeguards.'