John Paul Stevens

“ Officers conducting such a sweep must have a reasonable basis for believing that their search will reduce the danger of harm to themselves or of violent interference with their mission; in short, the search must be protective. ”

“ As the Court indicates, Officer Frolich might, at the time of the arrest, reasonably have "look [ed] in" the already open basement door, ante, at 334, to ensure that no accomplice had followed Buie to the stairwell. But Officer Frolich did not merely "look in" the basement; he entered it. [2] That strategy is sensible if one wishes to search the basement. It is a surprising choice for an officer, worried about safety, who need not risk entering the stairwell at all. ”