Supreme Court Landmark Cases on Police Traffic Stops

When a police officer makes a traffic stop, the passenger, like the driver, is seized for Fourth Amendment purposes and may challenge the constitutionality of the stop. (Brendlin v. California (2007) 551 U.S. 249, 255-260.) In the context of an ordinary traffic stop, an officer may not pat down a driver or a passenger without a reasonable suspicion that the person may be armed and dangerous. (Knowles v. Iowa (1998) 525 U.S. 113, 118.) "Where a police officer observes unusual conduct which leads the officer reasonably to conclude in light of his or her experience that criminal activity may be afoot and that the persons with whom the officer is dealing may be armed and presently dangerous, where in the course of investigating this behavior the officer identifies himself or herself as a police officer and makes reasonable inquiries, and where nothing in the initial stages of the encounter serves to dispel the officer's reasonable fear for his or her own safety," the officer is entitled to conduct a carefully limited search of the outer clothing of such persons for the protection of the officer and others in the area in an attempt to discover weapons that might be used to assault the officer. (Terry v. Ohio (1968) 392 U.S. 1, 30 (Terry).) The police officer must be able to point to specific and articulable facts together with rational inferences therefrom that reasonably support a suspicion that the suspect is armed and dangerous. (Terry, supra, 392 U.S. at p. 20.) Where no specific and articulable facts are presented, the patdown search cannot be upheld. (People v. Dickey (1994) 21 Cal.App.4th 952, 956 (Dickey).) Circumstances that can give rise to a reasonable suspicion include, but are not limited to, the officer's knowledge of the methods used in criminal activity and the characteristics of persons engaged in such illegal practices, the characteristics of the area, and the behavior of a suspect who appears to be evading police contact. (United States v. Mendenhall (1980) 446 U.S. 544, 563-564.) The guiding principle, as in all cases arising under the Fourth Amendment, is "the reasonableness in all the circumstances of the particular governmental invasion of a citizen's personal security." (Terry, supra, 392 U.S. at p. 19.)