Writing for the Court, Justice John Paul Stevens held that the Fourth Amendment doesn’t permit a blanket, category-wide exception to the knock-and-announce requirement for felony drug investigations. Stevens recognized that felony drug investigations frequently involve threats of physical violence or the likelihood that evidence will be destroyed, but he noted that these risks are not present in every case and argued that creating a categorical exception presents two major concerns. First, such a rule “contains considerable overgeneralization” that would “impermissibly insulate from judicial review” cases that don’t present these risks. Second, the reasoning could, “relatively easily, be applied to others” such as armed bank robberies. Stevens warned that if a per se exception were permitted for every criminal category involving a risk of danger or destruction of evidence, “the knock-and-announce element of the Fourth Amendment’s reasonableness requirement would be meaningless.”

To strike the proper balance between law enforcement concerns and individual privacy, Stevens established that a no-knock entry is constitutionally justified only when police have “reasonable suspicion that knocking and announcing their presence, under the particular circumstances, would be dangerous or futile, or that it would inhibit the effective investigation of the crime by, for example, allowing the destruction of evidence.” Stevens acknowledged that such a standard isn’t high, but he emphasized that the police must meet it on a case-by-case basis whenever the reasonableness of a no-knock entry is challenged. Stevens added that individual privacy interests affected by a sudden, unannounced entry “should not be unduly minimized” because they provide the individual with an opportunity to prepare themselves and “comply with the law and to avoid the destruction of property.”

Applying this case-by-case standard, Stevens concluded that the officers’ unannounced entry into Richards’ motel room didn’t violate the Fourth Amendment. Stevens explained that while the officers’ proposed no-knock authorization was removed from the search warrant, their actions “must be evaluated as of the time they entered the motel room” because a magistrate cannot predict every circumstance that the officers will face on the scene. Stevens argued that once Officer Pharo knocked on the door and Richards cracked it open only to spot a uniformed officer and quickly slam it, the officers possessed a reasonable suspicion that Richards might destroy evidence if given the opportunity. Combined with the “easily disposable nature of the drugs,” these circumstances justified the officers’ decision to force immediate entry despite the lack of explicit authorization in the warrant. Ultimately, Stevens concluded that the Fourth Amendment prohibits a blanket exception to the knock-and-announce requirement for felony drug investigations, but the officers’ entry into Richards’ motel room was valid because they possessed reasonable suspicion.