⚖ Oral Arguments, with Context

A Denver undercover fentanyl buy raises a question: what did police know before arresting Derris Mayberry? In March 2024, a woman offered to get pills for an undercover officer, went into a nearby alley to Mayberry, and returned with fentanyl. Officers arrested him at a nearby bus stop, then found a gun, more pills, and the marked cash used in the purchase. Mayberry asked the district court to exclude evidence from that search, arguing the arrest lacked probable cause; the judge rejected his challenge. Probable cause requires reliable facts known before arrest that would lead a reasonable officer to believe the person committed a crime; a later search cannot justify the arrest retroactively. Here, the lawyers dispute whether officers reliably saw a hand-to-hand exchange, and whether the undercover purchase otherwise linked Mayberry to the pills. On appeal, the judges review factual findings for clear error but decide the legal probable-cause question afresh.

United States v. Mayberry (No. 25-1232) — U.S. Court of Appeals for the Tenth Circuit, argued September 16, 2026.