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Reasonable Suspicion and the Investigative Traffic Stop

The United States Supreme Court has given law enforcement officers the right to perform investigative stops based on reasonable suspicion.   The Court has stated that “reasonable suspicion entails some minimal level of objective justification for making a stop -- that is, something more than an inchoate and unparticularized suspicion or ‘hunch,’ but less than the level of suspicion required for probable cause.”  One of the first cases to use reasonable suspicion is Terry v. Ohio in 1968.  The Court has continued to grant officers the use of reasonable suspicion for the basis of an investigative stop through the years including the case of Kansas v. Glover in 2020.  That is more than 50 years of case law supporting law enforcement’s use of reasonable suspicion to justify an investigative stop.  This article will discuss five cases dealing with reasonable suspicion. 

The first case is Terry v. Ohio, 392 U. S. 1 (1968).  This case involved a police officer who observed two men walking back and forth in front of a store window 24 times.  The officer confronted the men.  The officer turned one of the men around and patted down his outer clothing.  The officer found a handgun.  The Court found that the officer’s conduct was reasonable under the 4th Amendment.  The Court stated, “the police should be allowed to ‘stop’ a person and detain him briefly for questioning upon suspicion that he may be connected with criminal activity.”

Now we jump ahead to the 1980s.  In the case of United States v. Cortez, 449 U. S. 411, (1981), Border Patrol agents found evidence that someone was smuggling people into the United States from Mexico.  During their investigation, they were able to determine that this was occurring at night and they were using a vehicle to transport the people once they got into this country.  The agents saw a camper drive past them that could be used to transport a group of people.  A few minutes later, the same camper drove past them traveling in the opposite direction.  The agents stopped the camper and found the smuggled individuals inside.  The Court found that the agent’s conduct was reasonable.  The Court stated “the officers must have a particularized and objective basis for suspecting the particular person stopped of criminal activity. The process of assessing all of the circumstances does not deal with hard certainties, but with probabilities, and the evidence collected must be weighed as understood by those versed in the field of law enforcement. Also, the process must raise suspicion that the particular individual being stopped is engaged in wrongdoing.”

Next case to discuss is the case of United States v. Sokolow, 490 U. S. 1, (1989). In this case, DEA agents stopped a person inside the Honolulu Airport.  He paid for his ticket in cash, the phone number associated with the ticket did not belong to him and he had only carry-on luggage.  He had over 1,000 grams of cocaine in his bag.  The Court found that the agent’s conduct was reasonable.  The Court stated that when you look at the totality of the circumstances, not just a few facts, the agents had reasonable suspicion to stop the person and held that the subsequent arrest was valid.

Skipping ahead almost 25 years, we have the case of Prado Navarette v. California, 572 U. S. 393, (2014).  In this case, a motorist was run off the road by a reckless driver.  The motorist called 911 and stated they were run off the road by a drunk driver.  The caller described the vehicle and license number.  A California Highway Patrol officer was dispatched to investigate.  The officer found the suspect vehicle and followed it for a short period.  The officer did not see any reason to stop the vehicle but had the 911 call that stated the driver was possibly intoxicated.  The officer stopped the vehicle.  On the approach, the officer smelled marijuana and found 30 pounds of the stuff in the bed of the truck.  The Court stated that the 911 call with the description and license plate of the vehicle was trustworthy enough to support reasonable suspicion.  Therefore, the arrest was valid.

The final case is Kansas v. Glover which was decided in April 2020.  In this case, a Kansas deputy sheriff ran the license plate of a vehicle and found that the driver’s license of the owner was revoked.  The deputy stopped the vehicle and arrested the driver for having a revoked driver’s license.  The Court stated that it was reasonable for the deputy to believe that the owner of the vehicle was actually the driver.  The Court stated that the computer return that the owner’s license was revoked was also reasonable.  The Court found that the deputy had reasonable suspicion to stop the driver and subsequently arrest them for having a revoked driver’s license.

These five cases are just some of the cases in which the United States Supreme Court has held that law enforcement officers may stop a person temporarily to investigate a possible crime based on reasonable suspicion.  These cases help law enforcement officers keep our roads safe by giving them the authority stop a motorist suspected of driving while intoxicated based solely on reasonable suspicion.


This article was written by Kevin Ryan.  He is the Lead Instructor for the Texas SFST Program.  He has 35 years of law enforcement experience and has been an SFST Instructor since 1991.  Feel free to contact us at info@txsfst.org if you have any questions or would like to host a SFST Refresher class.  Stay safe and be aware of your surroundings.