On January 14, 2026, the Supreme Court in Case v. Montana resolved when, under the Fourth Amendment, law enforcement may enter a home without a warrant to render aid in response to a public safety emergency inside. Prior to the decision, federal appeals courts and state courts of last resort had disagreed about the quantum of proof law enforcement needed to support such a warrantless entry; some courts demanded that law enforcement possess "probable cause" to justify the entry, while others set a standard below probable cause. In Case, the Supreme Court unanimously held that law enforcement need not possess probable cause, reasoning that probable cause is a concept applicable to law enforcement's criminal or investigative functions, not law enforcement's public safety responsibilities.
This Sidebar addresses the Supreme Court's ruling in Case. It first provides an overview of the Fourth Amendment, the emergency-aid exception to the warrant requirement, and the judicial split regarding the legal test applicable to this exception. It then summarizes the Supreme Court's majority opinion as well as the two concurrences. The Sidebar closes with considerations for Congress.
The Fourth Amendment reads, in part, "The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause." The Supreme Court has made clear that the Fourth Amendment guards against only certain governmental intrusions and that there is no unbounded "right of privacy" or right to be "let alone." Rather, the Fourth Amendment is implicated only if a "search" or "seizure" occurs.
A cognizable Fourth Amendment "search" generally involves government (1) intrusion upon a person's reasonable expectation of privacy, or (2) trespass upon a constitutionally protected space. The Fourth Amendment typically requires that searches be conducted only pursuant to a warrant predicated on "probable cause," or a "fair probability" that the search will reveal evidence of criminal activity. This quantum of proof is lower than a preponderance of the evidence (the more-likely-than-not standard). For instance, the Supreme Court determined that a police officer who found cocaine in a vehicle had probable cause to arrest all three occupants, because, absent evidence pointing to a particular individual, there was a fair probability that the cocaine belonged to one of them.
A search of a "constitutionally protected" area conducted without a warrant is "presumptively unconstitutional." Of these areas, the home lies at the "very core" of the Fourth Amendment's protections. "[B]ecause the ultimate touchstone of the Fourth Amendment is 'reasonableness,'" the Court has explained that "the warrant requirement is subject to certain exceptions." For example, the Court has determined that a police officer need not possess a warrant to pull over a vehicle for a purported traffic violation or to pat down an individual—initial intrusions that fall short of an arrest or digging into the pockets of the individual. The Court has recognized that as the severity of the intrusion lessens, so too does the quantum of proof needed by the government to support that intrusion. For this "stop" and "frisk" exception to the warrant requirement, law enforcement need only possess "reasonable suspicion," not probable cause. To establish reasonable suspicion, officers must be able to point to individualized and articulable facts supporting the intrusion on the person's constitutionally protected interests.
Another exception to the warrant requirement applies when law enforcement officers render emergency assistance under certain circumstances. This "emergency-aid" exception recognizes that while law enforcement frequently engages in duties related to crime, such as to prevent and investigate criminal activity, and to preserve evidence of such activity, they also engage in functions unrelated to crime, such as to promote public safety. The "emergency-aid" exception reflects this non-criminal function, and applies when law enforcement responds to emergency or crisis situations in which individuals pose an immediate threat to themselves or others, or in which a person is in need of immediate medical attention. Illustrating this exception, the Supreme Court commented that it would "defy reason" to insist upon a warrant before firemen could enter a burning building to rescue and attend to those inside.
The "emergency-aid" exception differs from the "exigent circumstances" exception to the warrant requirement in that the latter captures situations in which law enforcement is performing a crime-related function, but the time it would take to secure a warrant would frustrate those crime-related interests. For example, the Supreme Court has held under the exigent circumstances doctrine that a "warrantless entry to prevent the destruction of evidence is reasonable and thus allowed."
The "emergency-aid" exception also may be distinguished from the "community caretaking" exception. In 2021, the Court in Caniglia v. Strom explained the "community caretaking" exception is also premised on the fact that law enforcement may perform certain non-criminal "civic functions," such as responding to disabled vehicles and accidents. The Court cautioned, however, that "this recognition that police officers perform many civic tasks in modern society was just that—a recognition that these tasks exist, and not an open-ended license to perform them anywhere." The "community caretaking" exception thus may be contrasted with the "emergency-aid" exception in both temporal and spatial terms: community caretaking need not be predicated on a true emergency and it cannot alone justify a warrantless entry into the home.
In 2006, the Supreme Court announced in Brigham City v. Stuart that law enforcement action under the emergency-aid exception is "'reasonable' under the Fourth Amendment . . . 'as long as the circumstances, viewed objectively, justify [the] action.'" In that case, the Court upheld police officers' warrantless entry into a home, reasoning that the officers had an "objectively reasonable basis" for their belief that an injured individual inside might have needed medical help and that ongoing fighting in the home could have led to further injury. The Court reaffirmed in the 2009 case Michigan v. Fisher that law enforcement may enter a home without a warrant under the emergency-aid exception if the officers have "'an objectively reasonable basis for believing' . . . that 'a person within [the house] is in need of immediate aid.'" There, the Court determined that the officers' warrantless entry into the home was objectively reasonable, pointing to evidence of a damaged car in the driveway suggestive of a possible accident, drops of blood indicating that an occupant was injured, and an occupant screaming and throwing projectiles with the potential to injure himself or others. In the course of its opinion, the Court clarified that "[o]fficers do not need ironclad proof of 'a likely serious, life-threatening' injury to invoke the emergency aid exception."
These cases established that law enforcement must have an "objectively reasonable basis" for believing a person in a home is seriously injured or in danger, but the Court did not specify the quantum of proof required to support that basis. While the lower court in Brigham City had incorporated the "probable cause" standard into its emergency-aid test, the Court did not address whether probable cause was necessary for warrantless emergency-aid entry. The Fisher Court clarified that proof of emergency conditions need not be "ironclad," but did not specify what lesser degree of proof would suffice to establish reasonableness in this context. Federal courts of appeal have taken disparate approaches to this question. The U.S. Courts of Appeals for the Second, Eleventh, and D.C. Circuits (referenced here by their circuit names only) required law enforcement's belief to be supported by some formulation of a probable cause standard. The D.C. Circuit, for example, understood the emergency-aid exception to excuse the need for a warrant without relaxing the general requirement of probable cause that otherwise applies to law enforcement entry into a home; that is, much like in the case of a warrantless arrest, the emergency does not disturb the underlying requirement that officers have probable cause to believe the facts triggering the exception. By contrast, other circuits, including the First, Eighth, and Tenth Circuits, did not require a showing of probable cause to justify warrantless entries for emergency aid, asserting, for example, that Fisher "makes no mention of probable cause" and that requiring probable cause could "frustrate" the public safety role of law enforcement. The petitioner in Case v. Montana characterized the standard adopted by these three circuits as akin to reasonable suspicion.
The petitioner in Case was a defendant in a Montana state criminal case implicating the emergency-aid exception to the Fourth Amendment warrant requirement. He argued that his case was appropriate for Supreme Court review in light of the aforementioned circuit split, and the Court granted certiorari to address the outstanding question of whether the emergency-aid exception necessitates a showing of probable cause.
Police entered the petitioner's house following a report from the petitioner's ex-girlfriend that he was either at risk of suicide or had already made a suicide attempt. Based on what they already knew of the petitioner's mental health issues and their observations through the window of an empty handgun holster and what they assumed to be a suicide note, officers decided to enter the home to render emergency aid. When they entered an upstairs bedroom, the petitioner emerged from a closet holding an item one officer took for a gun, and the officer fired on the petitioner. Police recovered a gun from next to where the petitioner was standing. The petitioner survived and was charged locally with assaulting a police officer.
The petitioner moved to suppress all evidence deriving from the officers' warrantless entry to his home on the grounds that such entry violated the Fourth Amendment's prohibition on unreasonable searches and seizures. The trial court denied his motion, and the Supreme Court of Montana affirmed. The Montana court relied on Montana's "community caretaker doctrine," which under state judicial precedent authorized police to enter a home in "non-criminal situations where a warrantless entry is essential to ensure the wellbeing of a citizen, but that would otherwise be forbidden for lack of criminal activity and probable cause." The petitioner had argued that, pursuant to the Supreme Court's holding in Caniglia, "the only circumstance where a peace officer may enter a home without a warrant or consent is when there are both exigent circumstances and probable cause for violation of a criminal statute." The Montana Supreme Court rejected that argument, reasoning that such a rule would unduly narrow police officers' caretaking obligations and "impede an officer's duty to ensure the wellbeing of a citizen in imminent peril." Instead, the court explained that, pursuant to its community caretaker doctrine, there must be "objective, specific, and articulable facts from which an experienced officer would suspect" that a citizen needs emergency aid before officers may stop and investigate. Officers may then take "appropriate action" to help if needed, but once "peril has been mitigated," any further law enforcement activity constitutes a seizure implicating the Fourth Amendment and additional protections under the Montana Constitution.
Applying that analysis to the facts at hand, the court found that the officers appropriately suspected that the petitioner was in need of help based on their observations at his home and the information they received from his ex-girlfriend. The court further determined that the officers' actions, including announcing their presence at the house, shouting that they were there to help, and sweeping the house with firearms drawn, were "appropriate for mitigating peril." After the petitioner was shot, however, officers took actions at his home that "'morphed' from a welfare check to an arrest, for which probable cause would ordinarily be required." Nonetheless, the court found that the petitioner had "knowingly or purposefully caused reasonable apprehension of serious bodily injury" and "had thus assaulted" the officer "before the welfare check morphed into an arrest," giving rise to probable cause for that arrest.
The petitioner appealed to the Supreme Court of the United States, and the Justices unanimously affirmed his conviction. In an opinion authored by Justice Kagan, the Court reviewed the trio of previous cases on the emergency exception discussed above: Brigham City, Fisher, and Caniglia. The Court concluded that the Montana Supreme Court's reliance on the "community caretaking doctrine" was "ill-advised, given that Caniglia contrasted 'community caretaking' with 'render[ing] emergency assistance' and concluded that the former cannot alone justify a warrantless home entry." The Court further explained that the applicable test from Brigham City differed from that embodied in Montana's community caretaking doctrine. Where Brigham City requires only "an objectively reasonable basis for believing" emergency aid is necessary, the Montana test determined the "reasonableness" of a warrantless entry by reference to "specific and articulable facts" from which officers could "suspect" that a person needed help. The Court found that analysis mistakenly evoked a different test: the test for brief, investigative street stops under Terry v. Ohio, which requires "reasonable suspicion."
The petitioner had argued that the "objectively reasonable basis" test from Brigham City should be read as "sounding in probable cause," requiring that officers have probable cause to believe a requisite emergency exists. The Court rejected the argument that the "probable cause" standard should apply as a "spin" on the Brigham City test, saying that the probable cause standard is "peculiarly related to criminal investigations" and that law surrounding the standard "would fit awkwardly, if at all, the non-criminal, non-investigatory setting at issue here." The Court reasoned that this distinction was why the standard in Brigham City "asked simply whether an officer had 'an objectively reasonable basis for believing' that his entry was direly needed to prevent or deal with serious harm."
In evaluating the particulars of the petitioner's situation, the Court explained that objective reasonableness must be determined in light of the "totality of the circumstances." The petitioner argued that the officers were objectively unreasonable in their evaluation of the situation because only by entering the home did they trigger the possibility of "suicide-by-cop." The Court found that the possibility "that Case could provoke a confrontation" was just one of several circumstances to consider—the officers also had their own observations and information from his ex-girlfriend suggesting that the petitioner might "already have shot himself or would do so absent intervention." The Court concluded that the officers' decision "to enter his home to prevent that result—even at some significant risk to themselves—was (at the least) reasonable. The Fourth Amendment did not require them, as Case now argues, to leave him to his fate."
Justice Sotomayor and Justice Gorsuch wrote separate concurring opinions. Justice Sotomayor wrote "separately to underscore the unique considerations that law enforcement and courts should bear in mind when assessing whether there is an 'objectively reasonable basis to believe' that a person experiencing a mental-health crisis" requires emergency aid from law enforcement. She observed that given the heightened risk of violent confrontation between police and those suffering from mental illness, objective reasonableness may call for using various de-escalation techniques rather than warrantless entry. Justice Gorsuch wrote separately to emphasize that the emergency-aid exception to the Fourth Amendment's warrant requirement derives from common law roots.
Because the Court's ruling in Case addresses a constitutional rule, courts could find that Congress is not authorized to expand the scope of the emergency-aid exception. Congress still has other options. For example, in another context, Congress has enacted legislation authorizing law enforcement to break open doors or windows to execute a warrant in certain circumstances. The Court has held that law to be "controlling" with respect to warrantless entries as well. Congress could enact similar legislation governing when and how federal law enforcement may avail itself of the emergency-aid exception to the warrant requirement. With respect to mental health emergencies specifically, Congress has previously authorized grant funding for "multi-disciplinary teams that . . . coordinate, implement, and administer models to address mental health calls that include specially trained officers and mental health crisis workers responding to those calls together." In the federal law enforcement context, Congress has the option to impose such a model directly. Congress could also choose to leave warrantless entry in mental health and other emergencies to the discretion of law enforcement, subject to review by courts evaluating the existence of an "objectively reasonable basis" for the exercise of that discretion in particular cases.