Federal Appeals Ruling Tackles Issues of Attempted Detentions, Flight and When Probable Cause is Needed

By Robert Phillips  
Deputy District Attorney (Ret).

• Attempted detentions 
• Flight and probable cause to arrest 

United States v. Hamilton (9th Cir. Mar. 24, 2025) 131 F.4th 1087 

Rule: An attempted, but unsuccessful, detention, does not implicate the Fourth Amendment. Probable cause justifying a warrantless arrest exists where, under the totality of the facts and circumstances known to the arresting officer, a prudent person would have concluded that there was a fair probability that the suspect had committed a crime. Flight from law enforcement can be suggestive of wrongdoing and give rise to probable cause to arrest when coupled with preexisting specific reasons to suspect that the person fleeing may have engaged in criminal conduct. 

Facts: Around 2 a.m. on Feb. 14, 2021, officers from the San Francisco Police Department responded to reports of a shooting in the Tenderloin District. Police found three shooting victims. The decision doesn’t tell us, but apparently the resulting injuries were not life-threatening. The victims all described a “small Black man” as the shooter. The victims also told investigators that they observed the suspect having an altercation with a woman who had arrived at the scene in a taxi, after which the suspect forced her into a black Hyundai. All of this was also captured by a nearby surveillance camera. As the suspect drove away with the woman, he fired five rounds out of the driver’s side window, wounding the three victims. Obtaining the Hyundai’s license plate number from the surveillance camera, it was determined that the Hyundai was a rental that defendant Robert Hamilton had rented the day of the shooting.  

Information from the taxi company and rental information for the Hyundai led investigators to an address where it was determined that both the defendant and the woman lived. Screenshots later recovered from the Hyundai’s dash camera showed a Black man in the driver’s seat and a Black woman in the passenger seat, who appeared to be similar to defendant’s mug shot and a woman who it was determined to be his mother. A records check also revealed that Hamilton had prior firearm-related convictions.  

Two weeks later, on Feb. ....