By Brian MacMaster
Vehicle Stops Constitute Seizures
Vehicle stops make up a significant part of any patrol officer’s duties. The law surrounding vehicle stops, especially the extent of an officer’s permissible actions and the authorized duration of a stop, is not always clear. The purpose of this article is to clarify the current state of Fourth Amendment law related to those vehicle stops based on individualized suspicion. It does not address the law of vehicle stops as they apply to roadblocks, checkpoints, or other regulatory schemes. A vehicle stop is significant under the Fourth Amendment because it is considered a seizure. To justify such an intrusion on a citizen’s constitutional privacy rights, the officer must have an articulable, reasonable suspicion of a law violation (including civil offenses) or a public safety concern.
Sticking to the Purpose of the Stop; Duration of the Stop
The intrusion can only last as long as it reasonably takes to investigate the original purpose of the stop. Officers may perform tasks related to the stop, such as running a background check or checking for warrants, as long as these are completed within a timeframe reasonably needed to serve the stop’s purpose. Generally, inquiries that extend the duration of a stop and are unrelated to the original reason for the stop must be supported by reasonable suspicion of other illegal activity, or the stop must have shifted from a Fourth Amendment seizure to a consensual encounter. However, you may question the occupants of a lawfully detained vehicle about matters unrelated to the reason for the stop as long as the questioning does not extend the duration of the stop. A reviewing court will scrutinize the duration of the stop, and any activity unrelated to the purpose that measurably prolongs it will likely render the stop illegal. Extending the intrusion beyond the original purpose without the required additional reasonable suspicion or probable cause can lead to evidence being suppressed and may expose the officer to potential civil liability for violating a citizen’s constitutional rights.
Consensual Encounter
If, however, the stop has shifted to a genuinely consensual encounter, then the Fourth Amendment restrictions related to the particular stop and its duration end. Be mindful, however, that the restrictions could resume if the interaction again shifts to what could reasonably constitute a seizure. Whether a motorist is free to leave depends on what a reasonable person would believe in the same situation. This is where the officer’s behavior becomes essential. What is the tone of the officer’s voice? Is there physical contact? Is a weapon displayed? Does the officer explicitly tell the motorist they are free to leave? While informing the driver that they are free to leave is not a legal requirement, doing so, whether through words or actions, clearly signals that any further intrusion is consensual. Alternatively, if the officer, still in control of the stop with the motorist’s license, registration, and insurance card in hand, questions the motorist beyond the stop’s original purpose, such as asking about contraband or weapons or seeking consent to search the vehicle, the officer exceeds the initial scope of the stop. Without at least reasonable suspicion to justify such further inquiry, or without the stop having become a consensual encounter, these actions extend the stop unlawfully. An example would be prolonging a speeding stop to await the arrival of a drug-sniffing dog with no articulable, reasonable suspicion that unlawful drugs are aboard. The prosecution bears the burden of proving that the encounter was truly consensual and not merely a result of submission to authority.
“Kansas Two-Step”
Consider, for example, a federal district court ruling in what has become known as the “Kansas Two-Step.” A federal judge in July 2023 ruled that the Kansas Highway Patrol’s (KHP) “two-step” maneuver is unconstitutional, violating motorists’ Fourth Amendment rights against unreasonable searches and seizures. The ruling ordered the KHP to stop using the practice. According to the federal district court, the “Kansas Two-Step” is a tactic used by KHP troopers to prolong traffic stops and gather grounds for vehicle searches, often with drug-sniffing dogs. The maneuver typically involves a trooper completing the purpose of the stop—such as issuing a ticket or warning—and then walking away from the driver’s vehicle to create the impression that the stop is over. The trooper quickly returns to ask additional questions, initiating what the KHP argues is a “consensual encounter” legally separate from the original stop. The American Civil Liberties Union (ACLU) of Kansas argued that the practice coerces drivers into answering questions and consenting to searches because they do not feel free to leave. The federal district court judge stated that the KHP “waged war on motorists, especially out-of-state residents traveling between Colorado and Missouri on federal highway I-70 in Kansas.” The judge found the KHP targeted drivers from states where marijuana is legal, hoping to catch motorists in possession of marijuana, which is illegal in Kansas. In November 2023, the judge issued a permanent injunction requiring the KHP to inform drivers of their right to refuse questions or searches, obtain and document written consent to search, revise training curricula, provide ongoing training for troopers, and submit compliance reports twice a year. The court also ordered the state to pay over $2 million in legal fees to the plaintiffs. The KHP appealed the federal ruling to the 10th U.S. Circuit Court of Appeals, which granted a stay of the permanent injunction pending appeal. Oral arguments were held in November 2024, but a final decision has not yet been issued. Separately, in January 2025, the Kansas Court of Appeals issued a conflicting ruling in a case similar to the one at issue, upholding the practice as lawful under the existing state law. The legality of the “Kansas Two-Step” remains uncertain as courts consider these appeals.
Conclusion
In summary, the threshold for a valid vehicle stop is an officer’s articulable, reasonable suspicion of a violation of law or a public safety concern. It makes no difference that the officer may be motivated to stop a vehicle for reasons other than the suspected violation of the law. However, officers must limit their activity and questioning to the original purpose of the stop unless further reasonable suspicion or probable cause develops to extend the stop, or the stop becomes a truly consensual encounter. To do otherwise is to create an overly intrusive situation that may essentially constitute an arrest requiring probable cause, i.e., a “de facto arrest” or a “seizure tantamount to an arrest,” in violation of a person’s constitutional rights.