The Arizona Supreme Court has ruled that a state trooper had reasonable suspicion to conduct a traffic stop that led to a major marijuana trafficking conviction. On November 28, 2025, the court unanimously reversed a lower court decision that had thrown out the conviction of Asalia Guadalupe Alvarez-Soto. This ruling addresses two key questions: when can officers stop drivers for impeding traffic, and how should appellate courts evaluate video evidence?
The Traffic Stop and Drug Discovery
On December 14, 2018, Department of Public Safety Trooper Ashton Shewey patrolled Interstate 10 in Pinal County. He observed a 2007 Chevrolet Malibu traveling in the middle lane. Shewey ran its plate through his license-plate reader and conducted a border crossings check. The results revealed the vehicle was newly registered in Nogales, Arizona, and had crossed the U.S.-Mexico border multiple times.
Shewey followed the vehicle for several minutes. Initially, it traveled three miles per hour over the 75 mph speed limit. Then, it slowed to 70 mph. At that point, a red SUV passed Alvarez-Soto in the right lane.
Shewey decided to stop her for violating A.R.S. § 28-721(B). This statute requires slower traffic to move to the right lane. During the stop, he asked about her travel plans and requested consent to search the vehicle. She declined.
However, she agreed to a canine sniff. Shewey’s drug-detecting dog, Chili, alerted to the driver’s side of the car. Subsequently, Shewey searched the trunk. He discovered a suitcase containing 55 pounds of marijuana. As a result, the State charged Alvarez-Soto with possession and transportation of marijuana for sale.
How the Case Moved Through the Courts
Before trial, Alvarez-Soto moved to suppress the evidence. She argued that Shewey lacked reasonable suspicion for the traffic stop. The Pinal County Superior Court disagreed and denied her motion. It found the stop was justified.
A jury then convicted her on both marijuana counts. The court sentenced her to concurrent five-year prison terms. She appealed to the Arizona Court of Appeals.
In a split decision, the appellate court threw out her convictions. It ruled that Shewey lacked reasonable suspicion under A.R.S. § 28-721(B). Additionally, the court relied on a 2010 precedent called State v. Sweeney. That case suggested appellate courts should independently review video evidence. Using that standard, the appeals court reached a different conclusion than the trial court.
The State then petitioned the Arizona Supreme Court for review. The high court accepted the case because it presented a recurring issue of statewide importance.
The Supreme Court’s Ruling and Its Meaning
Vice Chief Justice John R. Lopez IV wrote the unanimous opinion. All seven justices joined it. The court addressed two key issues.
First, it ruled that Shewey had reasonable suspicion for the traffic stop. The Fourth Amendment allows officers to briefly detain someone. They must have specific facts suggesting a violation is occurring. Here, Shewey observed Alvarez-Soto traveling below the speed limit in the middle lane while another vehicle passed her on the right. His interpretation of the traffic law was objectively reasonable—even if other interpretations exist. The court also held that an officer’s subjective motive is irrelevant if the stop is objectively justified. Shewey’s interest in the vehicle’s border-crossing history did not undermine his valid traffic-violation basis.
Second, the court rejected one aspect of the 2010 Sweeney precedent: its standard for independent appellate review of video evidence. This may be the ruling’s most significant legal development. Under Sweeney, appellate courts could independently review video recordings because trial courts supposedly had no advantage in viewing them.
The Arizona Supreme Court rejected this approach. Trial courts remain uniquely situated to evaluate video evidence in context. They hear testimony explaining what videos depict, assess witness credibility, and integrate visual evidence with other facts. Appellate courts defer to trial court findings if the record reasonably supports them—the standard Sweeney had undermined. They may correct clear errors—such as a video plainly contradicting a finding—but must defer in ambiguous cases.
Effects of the Arizona Supreme Court Traffic Stop Ruling
This decision provides important guidance for law enforcement and lower courts throughout Arizona. It clarifies that an officer’s objectively reasonable interpretation of A.R.S. § 28-721(B)—which requires slower drivers to stay right—can justify a traffic stop.
Additionally, the court established a uniform standard for reviewing all types of evidence on appeal. The court reaffirmed that video recordings receive the same deferential treatment as other evidence. This promotes uniformity and reinforces trial courts’ roles as primary factfinders.
The case now returns to the Court of Appeals to address Alvarez-Soto’s claim that Shewey unlawfully extended the traffic stop.
