The Court was also concerned that requiring probable cause for a frisk would put an officer in unwarranted danger during the investigation. The "sole justification" for a frisk, said the Court, is the "protection of the police officer and others nearby." Because of this narrow scope, a frisk must be "reasonably designed to discover guns, knives, clubs, or other hidden instruments for the assault of the police officer." As long as an officer has reasonable suspicion, a stop and frisk is constitutional under the Fourth Amendment.