## Facts

- Border Patrol agents monitored a remote desert area in southern Arizona used for illegal border crossings and observed repeated groups of footprints leading to Arizona State Route 86.
- Agents identified a distinctive chevron-shaped shoeprint believed to belong to a guide and inferred recurring smuggling patterns (clear weekend nights, a predictable pickup point, and a likely eastbound return after pickup).
- After rain erased earlier tracks, agents predicted a new crossing on a Sunday night and set surveillance several miles east of the suspected pickup location between about 2:00 a.m. and 6:00 a.m.
- During that period, few vehicles passed; only two were large enough to transport a group.
- A pickup truck with a camper shell traveled west at about 4:30 a.m. and returned east at about 6:12 a.m., consistent with the predicted pickup-and-return pattern.
- Agents stopped the truck; Cortez was the driver and Hernandez-Loera the passenger.
- Hernandez-Loera’s shoes matched the distinctive chevron tread associated with the suspected guide.
- Cortez opened the camper, revealing several undocumented migrants; respondents were arrested and later convicted of transporting undocumented aliens.
- The district court denied a motion to suppress; the Ninth Circuit reversed for lack of sufficient basis to stop; the Supreme Court reversed the Ninth Circuit.

## Issues

1. Whether the Fourth Amendment permitted Border Patrol agents to make an investigative vehicle stop based on reasonable suspicion drawn from objective facts and inferences.
2. Whether reasonable suspicion must be evaluated by isolating each fact or by considering the totality of the circumstances as a whole.
3. Whether the agents had a particularized and objective basis to suspect this specific vehicle of transporting undocumented migrants.

## Decision

- The Supreme Court reversed the Ninth Circuit and held the investigative stop was supported by reasonable suspicion.
- The Court ruled that reasonable suspicion is determined by considering the totality of the circumstances—the whole picture—rather than discounting individual factors in isolation.
- The Court held the agents had a particularized and objective basis for suspecting the Cortez vehicle based on observed patterns, timing, location, and the truck’s movements consistent with predicted smuggling behavior.
- The Court accepted that trained officers may draw reasonable inferences from observed facts and probabilities when forming suspicion.
- The Court treated the stop as a limited investigatory detention proportional to the suspicion and therefore reasonable under the Fourth Amendment.

## Legal Principles

- Reasonable suspicion is assessed under the totality of the circumstances; courts evaluate the whole picture rather than atomizing facts.
- Officers must have a particularized and objective basis for suspecting the specific person or vehicle stopped of criminal activity.
- Reasonable suspicion may rest on rational inferences drawn by experienced law enforcement officers from objective observations.
- Investigative vehicle stops are permissible when the intrusion is limited and directly related to the circumstances justifying the stop.
- Roving patrol stops near the border require specific, articulable facts supporting reasonable suspicion; generalized or impermissible factors alone are insufficient.

## Conclusion

The Court held that the Border Patrol’s stop satisfied the Fourth Amendment because, viewed as a whole, the agents’ objective observations and experience-based inferences created a particularized and objective reasonable suspicion that the vehicle was involved in illegal alien transportation.


United States v. Cortez, 449 U.S. 411 (1981)