United States v. Brown — Fifth Circuit upheld firearm evidence found after a dog sniff during a traffic stop

Case
United States of America v. William Jefferson Brown, Jr.
Court
U.S. Court of Appeals for the Fifth Circuit
Judge
Clement; Haynes; Ramirez
Date Decided
August 17, 2026
Docket No.
25-50728
Topics
Fourth Amendment, Traffic Stops, Dog Sniffs, Firearm Possession
Source
Read the full opinion

Background

Police surveilled a Killeen, Texas residence after a confidential informant reported that narcotics would be delivered and sold there. Officers observed several brief visits consistent with drug sales, and another driver stopped after leaving the residence was arrested for possessing methamphetamine. Brown arrived carrying a backpack, entered the residence for a few minutes, and then drove away.

After another officer saw Brown commit a traffic violation, Officer Justin Asmus stopped him. Brown took time to obtain proof of insurance from his wife and initially resisted an instruction to exit the vehicle. Once Brown was outside, Asmus requested consent to search, which Brown denied, and then conducted a sniff using a dog already at the scene. The dog alerted within one minute—14 minutes after the stop began—and a search uncovered a revolver in Brown’s backpack. Brown conditionally pleaded guilty to possessing a firearm as a convicted felon and received a 120-month prison sentence after the district court denied his suppression motion.

The Court’s Holding

The Fifth Circuit affirmed, holding that the traffic stop was not unconstitutionally prolonged. Asmus promptly requested Brown’s license and insurance information and questioned him about his expired license. Any delay before the sniff resulted from Brown’s inability to produce insurance promptly, his arguing, and his unrelated conversation—not from a lack of diligence by the officer. Because the dog was already present and alerted within one minute, the sniff did not measurably extend the stop.

The court also held that reasonable suspicion independently justified the dog sniff. Asmus knew police were investigating the residence for narcotics trafficking, that Brown had carried a backpack inside for only a few minutes, and that Brown reached toward the passenger seat after being stopped. Viewed together, those circumstances supplied a particularized, objective basis to suspect additional criminal activity. Judge Haynes concurred in the judgment only.

Key Takeaways

  • A dog sniff does not violate the Fourth Amendment when it does not measurably extend the time reasonably needed to complete a traffic stop.
  • Delays attributable to a motorist’s conduct, including difficulty producing insurance and arguing with an officer, do not establish that police failed to pursue the traffic investigation diligently.
  • Brief activity at a suspected drug-trafficking location, combined with other observations during a stop, may collectively establish reasonable suspicion even if each fact appears innocent in isolation.

Why It Matters

The decision illustrates two independent grounds that can sustain a dog sniff during a traffic stop: the sniff may occur without adding measurable time to the traffic investigation, or additional detention may be supported by reasonable suspicion of other criminal activity. For suppression litigation, the chronology of the stop and the source of each delay remain central.

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