delivered the opinion of the Court.
We granted certiorari to decide whether an individual reasonably suspected of engaging in criminal activity may be *677detained for a period of 20 minutes, when the detention is necessary for law enforcement officers to conduct a limited investigation of the suspected criminal activity.
I — I
<1
On the morning of June 9, 1978, Agent Cooke of the Drug Enforcement Administration (DEA) was on patrol in an unmarked vehicle on a coastal road near Sunset Beach, North Carolina, an area under surveillance for suspected drug trafficking. At approximately 6:30 a. m., Cooke noticed a blue pickup truck with an attached camper shell traveling on the highway in tandem with a blue Pontiac Bonneville. Respondent Savage was driving the pickup, and respondent Sharpe was driving the Pontiac. The Pontiac also carried a passenger, Davis, the charges against whom were later dropped. Observing that the truck was riding low in the rear and that the camper did not bounce or sway appreciably when the truck drove over bumps or around curves, Agent Cooke concluded that it was heavily loaded. A quilted material covered the rear and side windows of the camper.
Cooke’s suspicions were sufficiently aroused to follow the two vehicles for approximately 20 miles as they proceeded south into South Carolina. He then decided to make an “investigative stop” and radioed the State Highway Patrol for assistance. Officer Thrasher, driving a marked patrol car, responded to the call. Almost immediately after Thrasher caught up with the procession, the Pontiac and the pickup turned off the highway and onto a campground road.1 Cooke and Thrasher followed the two vehicles as the latter drove along the road at 55 to 60 miles an hour, exceeding the speed limit of 35 miles an hour. The road eventually looped back to *678the highway, onto which Savage and Sharpe turned and continued to drive south.
At this point, all four vehicles were in the middle lane of the three right-hand lanes of the highway. Agent Cooke asked Officer Thrasher to signal both vehicles to stop. Thrasher pulled alongside the Pontiac, which was in the lead, turned on his flashing light, and motioned for the driver of the Pontiac to stop. As Sharpe moved the Pontiac into the right lane, the pickup truck cut between the Pontiac and Thrasher’s patrol car, nearly hitting the patrol car, and continued down the highway. Thrasher pursued the truck while Cooke pulled up behind the Pontiac.
Cooke approached the Pontiac and identified himself. He requested identification, and Sharpe produced a Georgia driver’s license bearing the name of Raymond J. Pavlo-vich. Cooke then attempted to radio Thrasher to determine whether he had been successful in stopping the pickup truck, but he was unable to make contact for several minutes, apparently because Thrasher was not in his patrol car. Cooke radioed the local police for assistance, and two officers from the Myrtle Beach Police Department arrived about 10 minutes later. Asking the two officers to “maintain the situation,” Cooke left to join Thrasher.
In the meantime, Thrasher had stopped the pickup truck about one-half mile down the road. After stopping the truck, Thrasher had approached it with his revolver drawn, ordered the driver, Savage, to get out and assume a “spread eagled” position against the side of the truck, and patted him down. Thrasher then holstered his gun and asked Savage for his driver’s license and the truck’s vehicle registration. Savage produced his own Florida driver’s license and a bill of sale for the truck bearing the name of Pavlovich. In response to questions from Thrasher concerning the ownership of the truck, Savage said that the truck belonged to a friend and that he was taking it to have its shock absorbers repaired. When Thrasher told Savage that he would be held *679until the arrival of Cooke, whom Thrasher identified as a DEA agent, Savage became nervous, said that he wanted to leave, and requested the return of his driver’s license. Thrasher replied that Savage was not free to leave at that time.
Agent Cooke arrived at the scene approximately 15 minutes after the truck had been stopped. Thrasher handed Cooke Savage’s license and the bill of sale for the truck; Cooke noted that the bill of sale bore the same name as Sharpe’s license. Cooke identified himself to Savage as a DEA agent and said that he thought the truck was loaded with marihuana. Cooke twice sought permission to search the camper, but Savage declined to give it, explaining that he was not the owner of the truck. Cooke then stepped on the rear of the truck and, observing that it did not sink any lower, confirmed his suspicion that it was probably overloaded. He put his nose against the rear window, which was covered from the inside, and reported that he could smell marihuana. Without seeking Savage’s permission, Cooke removed the keys from the ignition, opened the rear of the camper, and observed a large number of burlap-wrapped bales resembling bales of marihuana that Cooke had seen in previous investigations. Agent Cooke then placed Savage under arrest and left him with Thrasher.
Cooke returned to the Pontiac and arrested Sharpe and Davis. Approximately 30 to 40 minutes had elapsed between the time Cooke stopped the Pontiac and the time he returned to arrest Sharpe and Davis. Cooke assembled the various parties and vehicles and led them to the Myrtle Beach police station. That evening, DEA agents took the truck to the Federal Building in Charleston, South Carolina. Several days later, Cooke supervised the unloading of the truck, which contained 43 bales weighing a total of 2,629 pounds. Acting without a search warrant, Cooke had eight randomly selected bales opened and sampled. Chemical tests showed that the samples were marihuana.
*680B
Sharpe and Savage were charged with possession of a controlled substance with intent to distribute it in violation of 21 U. S. C. § 841(a)(1) and 18 U. S. C. §2. The United States District Court for the District of South Carolina denied respondents’ motion to suppress the contraband, and respondents were convicted.
A divided panel of the Court of Appeals for the Fourth Circuit reversed the convictions. Sharpe v. United States, 660 F. 2d 967 (1981). The majority assumed that Cooke “had an articulable and reasonable suspicion that Sharpe and Savage were engaged in marijuana trafficking when he and Thrasher stopped the Pontiac and the truck.” Id., at 970. But the court held the investigative stops unlawful because they “failed to meet the requirement of brevity” thought to govern detentions on less than probable cause. Ibid. Basing its decision solely on the duration of the respondents’ detentions, the majority concluded that “the length of the detentions effectively transformed them into de facto arrests without bases in probable cause, unreasonable seizures under the Fourth Amendment.” Ibid. The majority then determined that the samples of marihuana should have been suppressed as the fruit of respondents’ unlawful seizures. Id., at 971. As an:alternative basis for its decision, the majority held that the warrantless search of the bales taken from the pickup violated Robbins v. California, 453 U. S. 420 (1981). Judge Russell dissented as to both grounds of the majority’s decision.
The Government petitioned for certiorari, asking this Court to review both of the alternative grounds held by the Court of Appeals to justify suppression. We granted the petition, vacated the judgment of the Court of Appeals, and remanded the case for further consideration in the light of the intervening decision in United States v. Ross, 456 U. S. 798 (1982). United States v. Sharpe, 457 U. S. 1127 (1982).
*681On remand, a divided panel of the Court of Appeals again reversed the convictions. 712 F. 2d 65 (1983). The majority concluded that, in the light of Ross, it was required to “disavow” its alternative holding disapproving the warrant-less search of the marihuana bales. But, “[fjinding that Ross does not adversely affect our primary holding” that the detentions of the two defendants constituted illegal seizures, the court readopted the prior opinion as modified. Ibid. The majority declined “to reexamine our principal holding or to reargue the same issues that were addressed in detail in the original majority and dissenting opinions,” reasoning that its action complied with this Court’s mandate. The panel assumed that “[h]ad [this] Court felt that a reversal was in order, it could and would have said so.” Id., at 65, n. 1. Judge Russell again dissented.
We granted certiorari, 467 U. S. 1250 (1984), and we reverse.2
*682) — 1
A
The Fourth Amendment is not, of course, a guarantee against all searches and seizures, but only against unreasonable searches and seizures. The authority and limits of the Amendment apply to investigative stops of vehicles such as occurred here. United States v. Hensley, 469 U. S. 221, 226 (1985); United States v. Cortez, 449 U. S. 411, 417 (1981); Delaware v. Prouse, 440 U. S. 648, 663 (1979); United States v. Brignoni-Ponce, 422 U. S. 873, 878, 880 (1975). In Terry v. Ohio, 392 U. S. 1 (1968), we adopted a dual inquiry for evaluating the reasonableness of an investigative stop. Under this approach, we examine
“whether the officer’s action was justified at its inception, and whether it was reasonably related in scope to the circumstances which justified the interference in the first place.” Id., at 20.
As to the first part of this inquiry, the Court of Appeals assumed that the police had an articulable and reasonable suspicion that Sharpe and Savage were engaged in marihuana trafficking, given the setting and all the circumstances when the police attempted to stop the Pontiac and the pickup. 660 F. 2d, at 970. That assumption is abundantly supported by the record.3 As to the second part of the in*683quiry, however, the court concluded that the 30- to 40-minute detention of Sharpe and the 20-minute detention of Savage “failed to meet the [Fourth Amendment’s] requirement of brevity.” Ibid.
It is not necessary for us to decide whether the length of Sharpe’s detention was unreasonable, because that detention bears no causal relation to Agent Cooke’s discovery of the marihuana. The marihuana was in Savage’s pickup, not in Sharpe’s Pontiac; the contraband introduced at respondents’ trial cannot logically be considered the “fruit” of Sharpe’s detention. The only issue in this case, then, is whether it was reasonable under the circumstances facing Agent Cooke and Officer Thrasher to detain Savage, whose vehicle contained the challenged evidence, for approximately 20 minutes. We conclude that the detention of Savage clearly meets the Fourth Amendment’s standard of reasonableness.
The Court of Appeals did not question the reasonableness of Officer Thrasher’s or Agent Cooke’s conduct during their detention of Savage. Rather, the court concluded that the length of the detention alone transformed it from a Terry stop into a defacto arrest. Counsel for respondents, as ami-cus curiae, assert that conclusion as their principal argument before this Court, relying particularly upon our decisions in Dunaway v. New York, 442 U. S. 200 (1979); Florida v. Royer, 460 U. S. 491 (1983); and United States v. Place, 462 U. S. 696 (1983). That reliance is misplaced.
In Dunaway, the police picked up a murder suspect from a neighbor’s home and brought him to the police station, where, after being interrogated for an hour, he confessed. *684The State conceded that the police lacked probable cause when they picked up the suspect, but sought to justify the warrantless detention and interrogation as an investigative stop. The Court rejected this argument, concluding that the defendant’s detention was “in important respects indistinguishable from a traditional arrest.” 442 U. S., at 212. Dunaway is simply inapposite here: the Court was not concerned with the length of the defendant’s detention, but with .events occurring during the detention.4
In Royer, government agents stopped the defendant in an airport, seized his luggage, and took him to a small room used for questioning, where a search of the luggage revealed narcotics. The Court held that the defendant’s detention constituted an arrest. See 460 U. S., at 503 (plurality opinion); id., at 509 (Powell, J., concurring); ibid. (Brennan, J., concurring in result). As in Dunaway, though, the focus was primarily on facts other than the duration of the defendant’s detention — particularly the fact that the police confined the defendant in a small airport room for questioning.
The plurality in Royer did note that “an investigative detention must be temporary and last no longer than is necessary to effectuate the purpose of the stop.” 460 U. S., at 500. The Court followed a similar approach in Place. In that case, law enforcement agents stopped the defendant after his arrival in an airport and seized his luggage for 90 minutes to take it to a narcotics detection dog for a “sniff test.” We decided that an investigative seizure of personal property could be justified under the Terry doctrine, but that “[t]he length of the detention of respondent’s luggage alone precludes the conclusion that the seizure was reasonable in the absence of probable cause.” 462 U. S., at 709. However, the rationale underlying that conclusion was premised on the fact that the police knew of respondent’s arrival time *685for several hours beforehand, and the Court assumed that the police could have arranged for a trained narcotics dog in advance and thus avoided the necessity of holding respondent’s luggage for 90 minutes. “[I]n assessing the effect of the length of the detention, we take into account whether the police diligently pursue their investigation.” Ibid.; see also Royer, supra, at 500.
Here, the Court of Appeals did not conclude that the police acted less than diligently, or that they unnecessarily prolonged Savage’s detention. Place and Royer thus provide no support for the Court of Appeals’ analysis.
Admittedly, Terry, Dunaway, Royer, and Place, considered together, may in some instances create difficult line-drawing problems in distinguishing an investigative stop from a de facto arrest. Obviously, if an investigative stop continues indefinitely, at some point it can no longer be justified as an investigative stop. But our cases impose no rigid time limitation on Terry stops. While it is clear that “the brevity of the invasion of the individual’s Fourth Amendment interests is an important factor in determining whether the seizure is so minimally intrusive as to be justifiable on reasonable suspicion,” United States v. Place, supra, at 709, we have emphasized the need to consider the law enforcement purposes to be served by the stop as well as the time reasonably needed to effectuate those purposes. United States v. Hensley, 469 U. S., at 228-229, 234-235; Place, supra, at 703-704, 709; Michigan v. Summers, 452 U. S. 692, 700, and n. 12 (1981) (quoting 3 W. LaFave, Search and Seizure § 9.2, pp. 36-37 (1978)). Much as a “bright line” rule would be desirable, in evaluating whether an investigative detention is unreasonable, common sense and ordinary human experience must govern over rigid criteria.
We sought to make this clear in Michigan v. Summers, supra:
“If the purpose underlying a Terry stop — investigating possible criminal activity — is to be served, the police must under certain circumstances be able to detain the *686individual for longer than the brief time period involved in Terry and Adams [v. Williams, 407 U. S. 143 (1972)].” 452 U. S., at 700, n. 12.
Later, in Place, we expressly rejected the suggestion that we adopt a hard-and-fast time limit for a permissible Terry stop:
“We understand the desirability of providing law enforcement authorities with a clear rule to guide their conduct. Nevertheless, we question the wisdom of a rigid time limitation. Such a limit would undermine the equally important need to allow authorities to graduate their responses to the demands of any particular situation.” 462 U. S., at 709, n. 10.
The Court of Appeals’ decision would effectively establish a per se rule that a 20-minute detention is too long to be justified under the Terry doctrine. Such a result is clearly and fundamentally at odds with our approach in this area.
B
In assessing whether a detention is too long in duration to be justified as an investigative stop, we consider it appropriate to examine whether the police diligently pursued a means of investigation that was likely to confirm or dispel their suspicions quickly, during which time it was necessary to detain the defendant. See Michigan v. Summers, supra, at 701, n. 14 (quoting 3 W. LaFave, Search and Seizure § 9.2, p. 40 (1978)); see also Place, 462 U. S., at 709; Royer, 460 U. S., at 500. A court making this assessment should take care to consider whether the police are acting in a swiftly developing situation, and in such cases the court should not indulge in unrealistic second-guessing. See generally post, at 712-716 (Brennan, J., dissenting). A creative judge engaged in post hoc evaluation of police conduct can almost always imagine *687some alternative means by which the objectives of the police might have been accomplished. But “[t]he fact that the protection of the public might, in the abstract, have been accomplished by ‘less intrusive’ means does not, by itself, render the search unreasonable.” Cady v. Dombrowski, 413 U. S. 433, 447 (1973); see also United States v. Martinez-Fuerte, 428 U. S. 543, 557, n. 12 (1976). The question is not simply whether some other alternative was available, but whether the police acted unreasonably in failing to recognize or to pursue it.
We readily conclude that, given the circumstances facing him, Agent Cooke pursued his investigation in a diligent and reasonable manner. During most of Savage’s 20-minute detention, Cooke was attempting to contact Thrasher and enlisting the help of the local police who remained with Sharpe while Cooke left to pursue Officer Thrasher and the pickup. Once Cooke reached Officer Thrasher and Savage,5 he proceeded expeditiously: within the space of a few minutes, he examined Savage’s driver’s license and the truck’s bill of sale, requested (and was denied) permission to search the truck, stepped on the rear bumper and noted that the truck did not move, confirming his suspicion that it was probably overloaded. He then detected the odor of marihuana.
Clearly this case does not involve any delay unnecessary to the legitimate investigation of the law enforcement officers. Respondents presented no evidence that the officers were dilatory in their investigation. The delay in this case was *688attributable almost entirely to the evasive actions of Savage, who sought to elude the police as Sharpe moved his Pontiac to the side of the road.6 Except for Savage’s maneuvers, only a short and certainly permissible pre-arrest detention would likely have taken place. The somewhat longer detention was simply the result of a “graduate[d] . . . respons[e] to the demands of [the] particular situation,” Place, supra, at 709, n. 10.
We reject the contention that a 20-minute stop is unreasonable when the police have acted diligently and a suspect’s actions contribute to the added delay about which he complains. The judgment of the Court of Appeals is reversed, and the case is remanded for further proceedings consistent with this opinion.
Reversed and remanded.
Officer Thrasher testified that the respondents’ vehicles turned off the highway “[a]bout one minute” after he joined the procession. 4 Record 141. *682principle is wholly irrelevant when the defendant has had his conviction nullified and the government seeks review here. Thus, when confronted with precisely this situation in Florida v. Rodriguez, 469 U. S. 1 (1984) (per curiam), we did not hesitate to reach and decide the merits of the case; had we thought that we should decline to reach every constitutional issue that might become moot, we would have denied certiorari. Cf. Eisler v. United States, 338 U. S. 189, 194 (1949) (Murphy, J., dissenting) (“That the ease may become moot if a defendant does not return does not distinguish it from any other case we decide. For subsequent events may render any decision nugatory”).
We granted certiorari on June 18, 1984. On August 27, counsel for respondents notified the Court that respondents had become fugitives. On October 1, we directed counsel for respondents to file a brief as amicus curiae in support of affirmance of the Court of Appeals’ judgment. Because our reversal of the Court of Appeals’ judgment may lead to the reinstatement of respondents’ convictions, respondents’ fugitive status does not render this case moot. See United States v. Villamonte-Marquez, 462 U. S. 579, 581-582, n. 2 (1983); Molinaro v. New Jersey, 396 U. S. 365, 366 (1970) (per curiam).
Justice Stevens would have this Court adopt a rule that, whenever a respondent or appellee before the Court becomes a fugitive before we render a decision, we must vacate the judgment under review and remand with directions to dismiss the appeal. This theory is not supported by our precedents, and indeed would be a break with a recent decision. The line of authority upon which the dissent relies concerns the situation in which a fugitive defendant is the party seeking review here. In those very different cases, dismissal of the petition or appeal is based on the equitable principle that a fugitive from justice is “disentitled” to call upon this Court for a review of his conviction. See United States v. Campos-Serrano, 404 U. S. 293, 294-295, n. 2 (1971); Molinaro, supra, at 366; see also Estelle v. Dorrough, 420 U. S. 534, 541-542 (1975) (per curiam). This equitable
Agent Cooke had observed the vehicles traveling in tandem for 20 miles in an area near the coast known to be frequented by drug traffickers. Cooke testified that pickup trucks with camper shells were' often used to *683transport large quantities of marihuana. App. 10. Savage’s pickup truck appeared to be heavily loaded, and the windows of the camper were covered with a quilted bed-sheet material rather than curtains. Finally, both vehicles took evasive actions and started speeding as soon as Officer Thrasher began following them in his marked car. See n. 1, supra. Perhaps none of these facts, standing alone, would give rise to a reasonable suspicion; but taken together as appraised by an experienced law enforcement officer, they provided clear justification to stop the vehicles and pursue a limited investigation.
The pertinent facts relied on by the Court in Dunaway were that (1) the defendant was taken from a private dwelling; (2) he was transported unwillingly to the police station; and (3) he there was subjected to custodial interrogation resulting in a confession. See 442 U. S., at 212.
It was appropriate for Officer Thrasher to hold Savage for the brief period pending Cooke’s arrival. Thrasher could not be certain that he was aware of all of the facts that had aroused Cooke’s suspicions; and, as a highway patrolman, he lacked Cooke’s training and experience in dealing with narcotics investigations. In this situation, it cannot realistically be said that Thrasher, a state patrolman called in to assist a federal agent in making a stop, acted unreasonably because he did not release Savage based solely on his own limited investigation of the situation and without the consent of Agent Cooke.
Even if it could be inferred that Savage was not attempting to elude the police when he drove his car between Thrasher’s patrol car and Sharpe’s Pontiac — in the process nearly hitting the patrol car, see App. 17, 37 — such an assumption would not alter our analysis or our conclusion. The significance of Savage’s actions is that, whether innocent or purposeful, they made it necessary for Thrasher and Cooke to split up, placed Thrasher and Cooke out of contact with each other, and required Cooke to enlist the assistance of local police before he could join Thrasher and Savage.