MR. JUSTICE STEWART announced the judgment of the Court and delivered an opinion, in which MR. JUSTICE REHNQUIST joined.
The respondent was brought to trial in the United States District Court for the Eastern District of Michigan on a
At the hearing in the trial court on the respondent's motion to suppress, it was established how the heroin she was charged with possessing had been obtained from her. The respondent arrived at the Detroit Metropolitan Airport on a commercial airline flight from Los Angeles early in the morning on February 10, 1976. As she disembarked from the airplane, she was observed by two agents of the DEA, who were present at the airport for the purpose of detecting unlawful traffic in narcotics. After observing the respondent's conduct, which appeared to the agents to be characteristic of persons unlawfully carrying narcotics,
After returning the airline ticket and driver's license to her, Agent Anderson asked the respondent if she would accompany him to the airport DEA office for further questions. She did so, although the record does not indicate a verbal response to the request. The office, which was located up one flight of stairs about 50 feet from where the respondent had first been approached, consisted of a reception area adjoined by three other rooms. At the office the agent asked the respondent if she would allow a search of her person and handbag and told her that she had the right to decline the search if she desired. She responded: "Go ahead." She then handed Agent Anderson her purse, which contained a receipt for an airline ticket that had been issued to "F. Bush" three days earlier for a flight from Pittsburgh through Chicago to Los Angeles. The agent asked whether this was the ticket that she had used for her flight to California, and the respondent stated that it was.
A female police officer then arrived to conduct the search of the respondent's person. She asked the agents if the respondent had consented to be searched. The agents said that she had, and the respondent followed the policewoman into a private room. There the policewoman again asked the respondent if she consented to the search, and the respondent
It was on the basis of this evidence that the District Court denied the respondent's motion to suppress. The court concluded that the agents' conduct in initially approaching the respondent and asking to see her ticket and identification was a permissible investigative stop under the standards of Terry v. Ohio, 392 U.S. 1, and United States v. Brignoni-Ponce, 422 U.S. 873, finding that this conduct was based on specific and articulable facts that justified a suspicion of criminal activity. The court also found that the respondent had not been placed under arrest or otherwise detained when she was asked to accompany the agents to the DEA office, but had accompanied the agents "`voluntarily in a spirit of apparent cooperation.'" It was the court's view that no arrest occurred until after the heroin had been found. Finally, the trial court found that the respondent "gave her consent to the search [in the DEA office] and . . . such consent was freely and voluntarily given."
The Court of Appeals reversed the respondent's subsequent conviction, stating only that "the court concludes that this case is indistinguishable from United States v. McCaleb," 552 F.2d 717 (CA6 1977).
On rehearing en banc of the present case, the Court of Appeals reaffirmed its original decision, stating simply that the respondent had not validly consented to the search "within the meaning of [McCaleb]." 596 F.2d 706, 707.
The Fourth Amendment provides that "the right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated. . . ." There is no question in this case that the respondent possessed this constitutional right of personal security as she walked through the Detroit Airport, for "the Fourth Amendment protects people, not places," Katz v. United States, 389 U.S. 347, 351. Here the Government concedes that its agents had neither a warrant nor probable cause to believe that the respondent was carrying narcotics when
The Fourth Amendment's requirement that searches and seizures be founded upon an objective justification, governs all seizures of the person, "including seizures that involve only a brief detention short of traditional arrest. Davis v. Mississippi, 394 U.S. 721 (1969); Terry v. Ohio, 392 U.S. 1, 16-19 (1968)." United States v. Brignoni-Ponce, supra, at 878.
The distinction between an intrusion amounting to a "seizure" of the person and an encounter that intrudes upon no constitutionally protected interest is illustrated by the facts of Terry v. Ohio, which the Court recounted as follows: "Officer McFadden approached the three men, identified himself as a police officer and asked for their names. . . . When the men `mumbled something' in response to his inquiries, Officer McFadden grabbed petitioner Terry, spun him around so that they were facing the other two, with Terry between McFadden and the others, and patted down the outside of his clothing." Id., at 6-7. Obviously the officer "seized" Terry and subjected him to a "search" when he took hold of him, spun him around, and patted down the outer surfaces of his clothing, id., at 19. What was not determined in that case, however, was that a seizure had taken place before the officer physically restrained Terry for purposes of searching his person
Similarly, the Court in Sibron v. New York, 392 U.S. 40, a case decided the same day as Terry v. Ohio, indicated that not every encounter between a police officer and a citizen is an intrusion requiring an objective justification. In that case, a police officer, before conducting what was later found to have been an unlawful search, approached Sibron in a restaurant and told him to come outside, which Sibron did. The Court had no occasion to decide whether there was a "seizure" of Sibron inside the restaurant antecedent to the seizure that accompanied the search. The record was "barren of any indication whether Sibron accompanied [the officer] outside in submission to a show of force or authority which left him no choice, or whether he went voluntarily in a spirit of apparent cooperation with the officer's investigation." 392 U. S., at 63 (emphasis added). Plainly, in the latter event, there was no seizure until the police officer in some way demonstrably curtailed Sibron's liberty.
We adhere to the view that a person is "seized" only when, by means of physical force or a show of authority, his freedom of movement is restrained. Only when such restraint is imposed is there any foundation whatever for invoking constitutional safeguards. The purpose of the Fourth Amendment is not to eliminate all contact between the police and the citizenry, but "to prevent arbitrary and oppressive interference
Moreover, characterizing every street encounter between a citizen and the police as a "seizure," while not enhancing any interest secured by the Fourth Amendment, would impose wholly unrealistic restrictions upon a wide variety of legitimate law enforcement practices. The Court has on other occasions referred to the acknowledged need for police questioning as a tool in the effective enforcement of the criminal laws. "Without such investigation, those who were innocent might be falsely accused, those who were guilty might wholly escape prosecution, and many crimes would go unsolved. In short, the security of all would be diminished. Haynes v. Washington, 373 U.S. 503, 515." Schneckloth v. Bustamonte, 412 U. S., at 225.
We conclude that a person has been "seized" within the meaning of the Fourth Amendment only if, in view of all of the circumstances surrounding the incident, a reasonable person would have believed that he was not free to leave.
On the facts of this case, no "seizure" of the respondent occurred. The events took place in the public concourse. The agents wore no uniforms and displayed no weapons. They did not summon the respondent to their presence, but instead approached her and identified themselves as federal agents. They requested, but did not demand to see the respondent's identification and ticket. Such conduct, without more, did not amount to an intrusion upon any constitutionally protected interest. The respondent was not seized simply by reason of the fact that the agents approached her, asked her if she would show them her ticket and identification, and posed to her a few questions. Nor was it enough to establish a seizure that the person asking the questions was a law enforcement official. See Terry v. Ohio, 392 U. S., at 31, 32-33 (Harlan, J., concurring). See also ALI, Model Code of Pre-Arraignment Procedure § 110.1 (1) and commentary, at 257-261 (1975). In short, nothing in the record suggests that the respondent had any objective reason to believe that she was not free to end the conversation in the concourse and proceed on her way, and for that reason we conclude that the agents' initial approach to her was not a seizure.
Our conclusion that no seizure occurred is not affected by the fact that the respondent was not expressly told by the agents that she was free to decline to cooperate with their inquiry, for the voluntariness of her responses does not depend upon her having been so informed. See Schneckloth v. Bustamonte, supra. We also reject the argument that the only inference to be drawn from the fact that the respondent acted in a manner so contrary to her self-interest is that she was compelled to answer the agents' questions. It may happen that a person makes statements to law enforcement
The Court's decision last Term in Brown v. Texas, 443 U.S. 47, on which the respondent relies, is not apposite. It could not have been plainer under the circumstances there presented that Brown was forcibly detained by the officers. In that case, two police officers approached Brown in an alley, and asked him to identify himself and to explain his reason for being there. Brown "refused to identify himself and angrily asserted that the officers had no right to stop him," id., at 49. Up to this point there was no seizure. But after continuing to protest the officers' power to interrogate him, Brown was first frisked, and then arrested for violation of a state statute making it a criminal offense for a person to refuse to give his name and address to an officer "who has lawfully stopped him and requested the information." The Court simply held in that case that because the officers had no reason to suspect Brown of wrongdoing, there was no basis for detaining him, and therefore no permissible foundation for applying the state statute in the circumstances there presented. Id., at 52-53.
The Court's decisions involving investigatory stops of automobiles do not point in any different direction. In United States v. Brignoni-Ponce, 422 U.S. 873, the Court held that a roving patrol of law enforcement officers could stop motorists in the general area of an international border for brief inquiry into their residence status only if the officers reasonably suspected that the vehicle might contain aliens who were illegally in the country. Id., at 881-882. The Government did not contend in that case that the persons whose automobiles were detained were not seized. Indeed, the Government acknowledged that the occupants of a detained vehicle were required to respond to the officers' questions and on some occasions to produce documents evidencing their eligibility to be in the United States. Id., at 880. Moreover, stopping or diverting an automobile in transit, with the attendant opportunity for
Although we have concluded that the initial encounter between the DEA agents and the respondent on the concourse at the Detroit Airport did not constitute an unlawful seizure, it is still arguable that the respondent's Fourth Amendment protections were violated when she went from the concourse to the DEA office. Such a violation might in turn infect the subsequent search of the respondent's person.
The District Court specifically found that the respondent accompanied the agents to the office "`voluntarily in a spirit of apparent cooperation,'" quoting Sibron v. New York, 392 U. S., at 63. Notwithstanding this determination by the trial court, the Court of Appeals evidently concluded that the agents' request that the respondent accompany them converted the situation into an arrest requiring probable cause in order to be found lawful. But because the trial court's finding was sustained by the record, the Court of Appeals was mistaken in substituting for that finding its view of the evidence. See Jackson v. United States, 122 U. S. App. D. C. 324, 353 F.2d 862 (1965).
The question whether the respondent's consent to accompany the agents was in fact voluntary or was the product of duress or coercion, express or implied, is to be determined by the totality of all the circumstances, Schneckloth v. Bustamonte, 412 U. S., at 227, and is a matter which the Government has the burden of proving. Id., at 222, citing Bumper v. North Carolina, 391 U.S. 543, 548. The respondent herself did not testify at the hearing. The Government's evidence showed that the respondent was not told that she
On the other hand, it is argued that the incident would reasonably have appeared coercive to the respondent, who was 22 years old and had not been graduated from high school. It is additionally suggested that the respondent, a female and a Negro, may have felt unusually threatened by the officers, who were white males. While these factors were not irrelevant, see Schneckloth v. Bustamonte, supra, at 226, neither were they decisive, and the totality of the evidence in this case was plainly adequate to support the District Court's finding that the respondent voluntarily consented to accompany the officers to the DEA office.
Because the search of the respondent's person was not preceded by an impermissible seizure of her person, it cannot be contended that her apparent consent to the subsequent search was infected by an unlawful detention. There remains to be considered whether the respondent's consent to the search was for any other reason invalid. The District Court explicitly credited the officers' testimony and found that the "consent was freely and voluntarily given," citing Schneckloth v. Bustamonte, supra. There was more than enough evidence in this case to sustain that view. First, we note that the respondent, who was 22 years old and had an 11th-grade education, was plainly capable of a knowing consent. Second, it is especially significant that the respondent was twice expressly told that she was free to decline to consent to the search, and only thereafter explicitly consented to it. Although the Constitution does not require "proof of knowledge of a right to refuse as the sine qua non of an effective consent to a search," id., at 234 (footnote omitted), such knowledge
Counsel for the respondent has argued that she did in fact resist the search, relying principally on the testimony that when she was told that the search would require the removal of her clothing, she stated to the female police officer that "she had a plane to catch." But the trial court was entitled to view the statement as simply an expression of concern that the search be conducted quickly. The respondent had twice unequivocally indicated her consent to the search, and when assured by the police officer that there would be no problem if nothing were turned up by the search, she began to undress without further comment.
Counsel for the respondent has also argued that because she was within the DEA office when she consented to the search, her consent may have resulted from the inherently coercive nature of those surroundings. But in view of the District Court's finding that the respondent's presence in the office was voluntary, the fact that she was there is little or no evidence that she was in any way coerced. And in response to the argument that the respondent would not voluntarily have consented to a search that was likely to disclose the narcotics that she carried, we repeat that the question is not whether the respondent acted in her ultimate self-interest, but whether she acted voluntarily.
We conclude that the District Court's determination that the respondent consented to the search of her person "freely
It is so ordered.
MR. JUSTICE POWELL, with whom THE CHIEF JUSTICE and MR. JUSTICE BLACKMUN join, concurring in part and concurring in the judgment.
I join Parts I, II-B, II-C, and III of the Court's opinion. Because neither of the courts below considered the question, I do not reach the Government's contention that the agents did not "seize" the respondent within the meaning of the Fourth Amendment. In my view, we may assume for present purposes that the stop did constitute a seizure.
The relevant facts may be stated briefly. The respondent arrived at the Detroit Metropolitan Airport on a flight from Los Angeles. She was the last passenger to leave the aircraft.
Terry v. Ohio, 392 U.S. 1 (1968), establishes that a reasonable investigative stop does not offend the Fourth Amendment.
The public has a compelling interest in detecting those who would traffic in deadly drugs for personal profit. Few problems affecting the health and welfare of our population, particularly our young, cause greater concern than the escalating use of controlled substances. Much of the drug traffic
To meet this pressing concern, the Drug Enforcement Administration since 1974 has assigned highly skilled agents to the Detroit Airport as part of a nationwide program to intercept drug couriers transporting narcotics between major drug sources and distribution centers in the United States. Federal agents have developed "drug courier profiles" that describe the characteristics generally associated with narcotics traffickers. For example, because the Drug Enforcement Administration believes that most drugs enter Detroit from one of four "source" cities (Los Angeles, San Diego, Miami, or New York), agents pay particular attention to passengers who arrive from those places. See United States v. Van Lewis, 409 F.Supp. 535, 538 (ED Mich. 1976), aff'd, 556 F.2d 385 (CA6 1977). During the first 18 months of the program, agents watching the Detroit Airport searched 141 persons in 96 encounters. They found controlled substances in 77 of the encounters and arrested 122 persons. 409 F. Supp., at 539. When two of these agents stopped the respondent in February 1976, they were carrying out a highly specialized law enforcement operation designed to combat the serious societal threat posed by narcotics distribution.
Our cases demonstrate that "the scope of [a] particular intrusion, in light of all the exigencies of the case, [is] a central element in the analysis of reasonableness." Terry v. Ohio, supra, at 18, n. 15.
In reviewing the factors that led the agents to stop and question the respondent, it is important to recall that a trained law enforcement agent may be "able to perceive and articulate meaning in given conduct which would be wholly innocent to the untrained observer." Brown v. Texas, supra, at 52, n. 2. Among the circumstances that can give rise to reasonable suspicion are the agent's knowledge of the methods used in recent criminal activity and the characteristics of persons engaged in such illegal practices. Law enforcement officers may rely on the "characteristics of the
The two officers who stopped the respondent were federal agents assigned to the Drug Enforcement Administration. Agent Anderson, who initiated the stop and questioned the respondent, had 10 years of experience and special training in drug enforcement. He had been assigned to the Detroit Airport, known to be a crossroads for illicit narcotics traffic,
The agents observed the respondent as she arrived in Detroit from Los Angeles. The respondent, who appeared very nervous, engaged in behavior that the agents believed was designed to evade detection. She deplaned only after all other passengers had left the aircraft. Agent Anderson testified that drug couriers often disembark last in order to have a clear view of the terminal so that they more easily can detect government agents. Id., at 9. Once inside the terminal the respondent scanned the entire gate area and walked "very, very slowly" toward the baggage area. Id., at 10 (testimony of Agent Anderson). When she arrived there, she claimed no baggage. Instead, she asked a skycap for directions to the Eastern Airlines ticket counter located in a different terminal. Agent Anderson stood in line immediately behind the respondent at the ticket counter. Although she carried an American Airlines ticket for a flight from Detroit to Pittsburgh, she asked for an Eastern Airlines ticket. An airline employee gave her an Eastern Airlines boarding pass. Id., at 10-11. Agent Anderson testified that drug couriers frequently travel without
The District Court, which had an opportunity to hear Agent Anderson's testimony and judge his credibility, concluded that the decision to stop the respondent was reasonable.
The jurisprudence of the Fourth Amendment demands consideration of the public's interest in effective law enforcement as well as each person's constitutionally secured right to be free from unreasonable searches and seizures. In applying
MR. JUSTICE WHITE, with whom MR. JUSTICE BRENNAN, MR. JUSTICE MARSHALL, and MR. JUSTICE STEVENS join, dissenting.
The Court today concludes that agents of the Drug Enforcement Administration (DEA) acted lawfully in stopping a traveler changing planes in an airport terminal and escorting her to a DEA office for a strip-search of her person. This result is particularly curious because a majority of the Members of the Court refuse to reject the conclusion that Ms. Mendenhall was "seized," while a separate majority decline to hold that there were reasonable grounds to justify a seizure. MR. JUSTICE STEWART concludes that the DEA agents acted lawfully, regardless of whether there were any reasonable grounds for suspecting Ms. Mendenhall of criminal activity, because he finds that Ms. Mendenhall was not "seized" by the DEA agents, even though throughout the proceedings below the Government never questioned the fact that a seizure had occurred necessitating a showing of antecedent reasonable suspicion. MR. JUSTICE POWELL'S opinion concludes that even though Ms. Mendenhall may have been "seized," the seizure was lawful because her behavior while changing planes in the airport provided reasonable suspicion that she was engaging in criminal activity. The Court then concludes, based on the absence of evidence that Ms. Mendenhall resisted her detention, that she voluntarily consented to being taken to the DEA office, even though she in fact had no choice in the matter. This conclusion is inconsistent with our recognition that consent cannot be presumed from a
Beginning with Terry v. Ohio, 392 U.S. 1, 16 (1968), the Court has recognized repeatedly that the Fourth Amendment's proscription of unreasonable "seizures" protects individuals during encounters with police that do not give rise to an arrest. United States v. Brignoni-Ponce, 422 U.S. 873, 878 (1975); United States v. Martinez-Fuerte, 428 U.S. 543, 556 (1976); Delaware v. Prouse, 440 U.S. 648, 653 (1979). In Terry we "emphatically reject[ed]" the notion that a "stop" "is outside the purview of the Fourth Amendment because. . . [it is not a] `seizure' within the meaning of the Constitution." 392 U. S., at 16. We concluded that "the sounder course is to recognize that the Fourth Amendment governs all intrusions by agents of the public upon personal security, and to make the scope of the particular intrusion, in light of all the exigencies of the case, a central element in the analysis of reasonableness." Id., at 18, n. 15. Applying this principle,
Throughout the lower court proceedings in this case, the Government never questioned that the initial stop of Ms. Mendenhall was a "seizure" that required reasonable suspicion. Rather, the Government sought to justify the stop by arguing that Ms. Mendenhall's behavior had given rise to
MR. JUSTICE STEWART believes that a "seizure" within the meaning of the Fourth Amendment occurs when an individual's freedom of movement is restrained by means of physical force or a show of authority. Although it is undisputed that Ms. Mendenhall was not free to leave after the DEA agents stopped her and inspected her identification, App. 19, MR. JUSTICE STEWART concludes that she was not "seized" because he finds that, under the totality of the circumstances,
Assuming, as we should, that Ms. Mendenhall was "seized" within the meaning of the Fourth Amendment when she was stopped by the DEA agents, the legality of that stop turns on whether there were reasonable grounds for suspecting her of criminal activity at the time of the stop. Brown v. Texas, 443 U. S., at 51. To establish that there was reasonable suspicion for the stop, it was necessary for the police at least to "be able to point to specific and articulable facts which, taken together with rational inferences from those facts, reasonably warrant that intrusion." Terry v. Ohio, 392 U. S., at 21.
At the time they stopped Ms. Mendenhall, the DEA agents' suspicion that she was engaged in criminal activity was based solely on their brief observations of her conduct at the airport.
None of the aspects of Ms. Mendenhall's conduct, either alone or in combination, were sufficient to provide reasonable suspicion that she was engaged in criminal activity. The fact that Ms. Mendenhall was the last person to alight from a flight originating in Los Angeles was plainly insufficient to provide a basis for stopping her. Nor was the fact that her flight originated from a "major source city," for the mere proximity of a person to areas with a high incidence of drug activity or to persons known to be drug addicts, does not provide the necessary reasonable suspicion for an investigatory stop. Ybarra v. Illinois, 444 U.S. 85 (1979); Brown v. Texas, supra; Sibron v. New York, 392 U.S. 40, 62 (1968).
Whatever doubt there may be concerning whether Ms. Mendenhall's Fourth Amendment interests were implicated during the initial stages of her confrontation with the DEA agents, she undoubtedly was "seized" within the meaning of the Fourth Amendment when the agents escorted her from the public area of the terminal to the DEA office for questioning and a strip-search of her person. In Dunaway v. New York, 442 U.S. 200 (1979), we held that a person who accompanied police officers to a police station for purposes of interrogation undoubtedly "was `seized' in the Fourth Amendment sense," even though "he was not told he was under arrest." Id., at 207, 203. We found it significant that the suspect was taken to a police station, "was never informed that he was `free to go,'" and "would have been physically restrained if he had refused to accompany the officers or had tried to escape their custody." Id., at 212. Like the "seizure" in Dunaway, the nature of the intrusion to which Ms. Mendenhall was subjected when she was escorted by DEA agents to their office and detained there for questioning and a strip-search was so great that it "was in important respects indistinguishable from a traditional arrest." Ibid. Although Ms. Mendenhall was not told that she was under arrest, she in fact was not free to refuse to go to the DEA office
Because the intrusion to which Ms. Mendenhall was subjected when she was escorted to the DEA office is of the same character as that involved in Dunaway, probable cause, which concededly was absent, was required to support the intrusion.
The Court's suggestion that no Fourth Amendment interest possessed by Ms. Mendenhall was implicated because she consented to go to the DEA office is inconsistent with Dunaway
The Court recognizes that the Government has the burden of proving that Ms. Mendenhall consented to accompany the officers, but it nevertheless holds that the "totality of evidence was plainly adequate" to support a finding of consent.
Since the defendant was not present to testify at the suppression hearing, we can only speculate about her state of mind as her encounter with the DEA agents progressed from surveillance, to detention, to questioning, to seclusion in a private office, to the female officer's command to remove her clothing. Nevertheless, it is unbelievable
Because Ms. Mendenhall was being illegally detained at the time of the search of her person, her suppression motion should have been granted in the absence of evidence to dissipate the taint.
Briefs of amici curiae urging affirmance were filed by Bruce J. Ennis, Jr., for the American Civil Liberties Union; and by Terence F. MacCarthy and Carol A. Brook for the National Legal Aid and Defender Association.
The evidentiary record in the trial court is adequate to permit consideration of the contention. The material facts are not disputed. A major question throughout the controversy has been whether the respondent was at any time detained by the DEA agents. Counsel for the respondent has argued that she was arrested while proceeding through the concourse. The trial court and the Court of Appeals characterized the incident as an "investigatory stop." But the correctness of the legal characterization of the facts appearing in the record is a matter for this Court to determine. See Schneckloth v. Bustamonte, 412 U.S. 218, 226; Bumper v. North Carolina, 391 U.S. 543, 548-550.
There is no indication that the Government on appeal, before either the original panel of the Court of Appeals or the en banc court, ever questioned the understanding that the stop of Ms. Mendenhall constituted a "seizure" requiring reasonable suspicion. Neither the majority of the en banc court nor the dissenting judge questioned the District Court's acknowledgment that reasonable suspicion was required to justify the initial stop of Ms. Mendenhall. Even in its petition for certiorari, the Government did not ask this Court to review the question whether a "seizure" had occurred. In the course of arguing that the quantum of suspicion necessary to justify the stop was slight, the Government did note that it was "arguable" that Ms. Mendenhall had not been "seized," but it was content to assume that she had been. Pet. for Cert. 19.
"Q. Did you have a tip in this case?
"Q. You were going strictly on what you saw in the airport, is that right?
"A. A number of things, what my observations, her response to statements.
"Q. I'm just asking—
"A. (Interposing) All right, Itinerary.
"Q. You're going on what happened on February 10 without any prior information?
"Q. You did not know that Sylvia Mendenhall was traveling to Detroit with narcotics, did you?
"Q. Nor any Negro female traveling from Los Angeles on that date carrying narcotics, did you?
"A. No." App 18.
"Q. All right. Now, when you asked her to accompany you to the DEA office for further questioning, if she had wanted to walk away, would you have stopped her?
"A. Once I asked her to accompany me?
"A. Yes, I would have stopped her.
"Q. She was not free to leave, was she?
"A. Not at that point." App. 19.
"Q. Had she tried to leave that room when she was being accompanied by the female officer, would you have known?
"A. If she had attempted to leave the room?
"A. Well yes, I could say that I would have known.
"Q. And if she had tried to leave prior to being searched by the female officer, would you have stopped her?
"A. Yes." Id., at 21.
(You may find you have consented, without ever knowing why.)