The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized. - Fourth Amendment to the Constitution of the United States
Reasonable suspicion, like the related concept of probable cause, comes from the 4th Amendment's protection against unreasonable searches and seizures. Where probable cause, though, concerns having sufficient evidence to issue a warrant or make an arrest, reasonable suspicion pertains to police having sufficient evidence to detain, question, or frisk someone suspected of committing a crime.
What this means is that to detain and question someone, police must have more than a simple hunch that the suspect has been involved in criminal activity. Instead, the standard is this: Would a reasonable person conclude that the available evidence suggests that a crime has been, or soon will be, committed?
Law enforcement would most likely have "reasonable suspicion" to detain and question someone who:
- is running away from a crime scene;
- is driving a vehicle that is the same make and model as one involved in a crime;
- has physical characteristics matching those of someone sought for a crime;
- displays a gun or other weapon in a public area;
- or is seen on surveillance video leaving a building immediately after a theft is reported.
Each incident, however, has to be evaluated in light of its particular set of circumstances.
Detaining and questioning a suspect is referred to as a "Terry Stop," after the Supreme Court articulated the principles of reasonable suspicion in Terry V. Ohio (1968). As stated above, each incident presents a unique set of facts that must be interpreted to determine if enough evidence exists for police to detain and question. Moreover, the matter is complicated by numerous other rules, such as those that pertain to frisking. For instance, if bulges in clothing look like concealed weapons, police may frisk a suspect. However, police may not frisk a person merely because they suspect the presence of illegal drugs. Part of the criminal defense process is reviewing the facts surrounding a Terry Stop and, if necessary, challenging its legitimacy.
Given the complicated nature of the law relating to reasonable suspicion and probable cause, it's best to consult with an experienced criminal defense lawyer if you have questions about an instance when you or someone you know was detained, questioned, or arrested. Call me at 916-442-1200 for a free and confidential consultation.