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. 27, an investigator involved in the shooting investigation spotted Hamilton several blocks away from where the shooting had occurred. He advised other officers in the area that Hamilton was wanted for the Valentine’s Day shooting, that the gun used in the shooting had not yet been recovered, and that it was “highly likely” that defendant may have it on his person. The officers later testified that they knew the location where Hamilton was seen to be a “high-crime area” where drug sales, shootings, and other crimes routinely occur. Shortly afterward, a patrol officer in the area saw a Black man who matched Hamilton’s description. Several officers then met up and “devised a plan to take (Hamilton) into custody.” Two officers pulled up to Hamilton, on foot, in their patrol car. One of the officers told Hamilton that the officers needed to speak with him. Another called Hamilton by name, falsely telling him that there was a warrant for his arrest, and ordered him to stop. Hamilton ran. The officers chased him on foot for several blocks and said they observed Hamilton reach for his waistband. Because of this, the officers said they believed Hamilton was armed. During the case, one of the officers ordered Hamilton to show his hands and get on the ground. Hamilton continued running. Other officers caught up to him in their patrol car and tackled him. Hamilton was handcuffed and arrested. After the arrest, officers found a gun, marijuana, scales and $6,692. Indicted in federal court on a variety of charges included those related to the shooting two week earlier, Hamilton’s  motion to suppress the gun and other evidence found on his person was denied. Found guilty after a jury trial and sentenced to two years and three months in prison, he appealed. 

Held: The Ninth Circuit Court of Appeals affirmed. On appeal, Hamilton argued that the evidence found on his person should have been suppressed because the officers lacked the necessary probable cause to arrest him and because his arrest was executed in an unreasonable manner. The court rejected both arguments.  

(1) The Attempted Detention: The basic rules are simple enough: The Fourth Amendment protects “against unreasonable searches and seizures.” A detention is a seizure of the person. In evaluating the legality of a detention, “the ultimate touchstone of the Fourth Amendment is reasonableness.” (United States v. Anderson (9th Cir. 2024) 101 F.4th 586, 591.) In determining whether a reasonable suspicion (or probable cause) exists, a court is to consider the totality of the circumstances in assessing whether law enforcement acted reasonably. (See Samson v. California (2006) 547 U.S. 843, 848.)  

The district (trial) court concluded in this case that the officers had a lawful basis to stop and detain defendant because they reasonably suspected he had been involved in the Valentine’s Day shooting two weeks earlier, a conclusion Hamilton did not dispute. Hamilton argued instead that the officers’ attempt to stop him was unlawful because, subjectively, they intended to conduct an arrest, and not just a detention for investigation. The court ruled, however, that the officers’ initial intent is immaterial in that he ran before the officers could do anything other than order him to stop. In their initial approach, the officers only attempted a seizure; their attempt being unsuccessful. As noted by the Supreme Court: “[T]here is no seizure without actual submission; otherwise, there is at most an attempted seizure.” (Brendlin v. California (2007) 551 U.S. 249, 254.) Because no seizure occurred during the officers’ initial contact with Hamilton, the Fourth Amendment’s protections were not triggered. (California v. Hodari D. (1991) 499 U.S. 621, 626.)  

Also, it has long been the rule that “outside limited contexts such as an ‘inventory search or administrative inspection, an officer’s (subjective) motive [does not] invalidate[] objectively justifiable behavior under the Fourth Amendment.’” (Kentucky v. King (2011) 563 U.S. 452, 465.)  In other words, the officers’ subjective motivations in attempting to detain someone are irrelevant, and are not to be considered.  Rather, a court is to review such a situation from the perspective of the person who was seized; not that of the officers doing the seizing. In this case, defendant did not dispute that the officers had “‘objectively justifiable’ grounds to conduct an investigatory stop based on reasonable suspicion.” Had defendant not fled, and submitted to an immediate arrest instead, then a different analysis would apply; i.e., was there probable cause to arrest? But that is not what happened. The issue, as a result, was whether there was probable cause to arrest him at that point in time when he was finally caught and taken into physical custody, and not whether there was a reasonable suspicion to detain him before the pursuit began.   Kentucky v. King (2011) 563 U.S. 452, 465.) In other words, the officers’ subjective motivations in attempting to detain someone are irrelevant and are not to be considered. Rather, a court is to review such a situation from the perspective of the person who was seized, not of the officers doing the seizing. In this case, Hamilton did not dispute that the officers had “‘objectively justifiable’ grounds to conduct an investigatory stop based on reasonable suspicion.” Had he not fled and submitted to an immediate arrest instead, then a different analysis would apply: was there probable cause to arrest? But that is not what happened. The issue, as a result, was whether there was probable cause to arrest him at that point when he was caught and taken into physical custody, and not whether there was a reasonable suspicion to detain him before the pursuit began.   

(2) Flight and Probable Cause to Arrest: In challenging the existence of probable cause, Hamilton first argued that the officers poisoned any probable cause that might have existed by falsely claiming upon their initial approach that they had a warrant for his arrest. The court held that whether that claim was a lie or a mistake is irrelevant. Even assuming it was a lie, there was no constitutional violation. “Officers are not categorically prohibited from using deception in investigations.” (Lewis v. United States (1966) 385 U.S. 206, 208-209.)  

Recognizing that reasonable suspicion already existed, which Hamilton conceded, providing the officers with a lawful basis to stop and question him without a warrant, falsely claiming that a warrant existed did not detract from that reasonable suspicion or negate the officers’ legal right to stop and question the defendant.  

Hamilton further argued, however, that his eventual arrest was unlawful because the officers did not have the necessary probable cause to believe he had committed a crime. In determining whether probable cause existed after Hamilton was arrested, the court cited the general rule that: “(p)robable 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.’” (United States v. Struckman (9th Cir. 20100 603 F.3rd 731, 739.)  

In considering these “facts and circumstances,” “flight” is recognized as a significant factor. “The Supreme Court has previously held that ‘[h]eadlong flight – wherever it occurs – is the consummate act of evasion: It is not necessarily indicative of wrongdoing, but it is certainly suggestive of such.’ ...Even where an ‘individual has a right to ignore the police and go about his business...[f]light, by its very nature, is not “going about one’s business;” in fact, it is just the opposite.’” (Illinois v. Wardlow (200) 528 U.S. 119, 124-125.) Such flight, therefore, is to be considered as a significant addition to the “the totality of the facts and circumstances known to the arresting officer,” where “a prudent person would have concluded that there was a fair probability that the suspect had committed a crime.” (United States v. Struckman (9th Cir. 20210) 603 F.3rd 731, 739.) “(F)light is not per se suspicious.” “(C)onsistent with the Fourth Amendment’s totality standard, ‘[t]here may be circumstances where a person’s flight has a perfectly innocent and reasonable explanation’ and thus does not reasonably engender suspicion.”  

Under the circumstances of this case, however, the court determined that the defendant’s flight, when coupled with the pre-existing reasonable suspicion connecting defendant to an unlawful shooting two weeks earlier, particularly when considering the pursing officers’ observation of defendant “clutching” his waistband (as if possibly reaching for a weapon) as he fled, the totality of these circumstances provided the officers with the necessary probable cause to both believe he was armed and to arrest him. “For these reasons, when the officers tackled (Hamilton) to stop his flight, they had reason to conclude that there was a ‘fair probability that (Hamilton) had committed a crime,” thus justifying his arrest. 

Note: The court made this all a bit more confusing than it had to be. Simply stated, when, upon an attempted detention, a suspect runs, whether there’s legal justification for a detention is irrelevant because no detention occurs, at least until he is caught. However, that same flight, when coupled with enough other incriminating circumstances, such as when there is at least a pre-existing reasonable suspicion to believe he is the suspect in an earlier shooting case and where he appears to be reaching for a firearm in his waistband as he flees, may provide the necessary probable cause to believe (1) he committed the previous shooting, and (2) he is currently armed. Make sense   

Note, however, that this is not a blanket rule. It depends upon how much other evidence exists, in addition to the flight, tending to indicate that he was involved in the shooting under investigation or another crime. Here, there was plenty of such evidence.  

The court also noted that San Francisco’s Tenderloin District is known as a “high crime” area, considering this to be an important inculpatory addition to the element of the defendant’s flight. This simple fact has indeed been held to be a factor by the U.S. Supreme Court in Illinois v. Wardlow, supra, where it was ruled that flight occurring in a high crime area justifies the resulting detention.  

A concurring opinion here, however, suggests that such a fact should be given “little weight.” This justice, Solomon Oliver, Jr., from the Ohio Federal District Court, sitting by assignment,  notes that this is “because such a description, unless properly limited and factually based, can easily serve as a proxy for race or ethnicity.” (Citing United States v. Montero-Camargo (9th Cir. 2000) 208 F.3rd 1122, 1138.)  

California recognized this fact when its legislature enacted Penal Code § 745: The Racial Justice Act, or “RJA,” effective Jan. 1, 2021, and as amended Jan. 1, 2025. This important and far-reaching legislation requires courts to consider whether an arrest and/or prosecution is motivated by a bias based on race, ethnicity, or national origin. Indeed, we’re now getting piles of new cases demanding consideration of this factor. The Ninth Circuit does not mention this issue here in that there is no comparable federal legislation. But just note that this can be an issue in any California investigation, arrest, or prosecution, and one the federal courts won’t ignore for long.