Mr. Justice Rutledge
delivered the opinion of the Court.
Brinegar was convicted of importing intoxicating liquor into Oklahoma from Missouri in violation of the federal statute which forbids such importation contrary to the laws of any state. His conviction was based in part on the use in evidence against him of liquor seized from his automobile in the course of the alleged unlawful importation.
Prior to the trial Brinegar moved to suppress this evidence as having been secured through an unlawful search and seizure. The motion was denied, as was a renewal of the objection at the trial.
The Court of Appeals affirmed the conviction, 165 F. 2d 512, and certiorari was sought solely on the ground that the search and seizure contravened the Fourth Amendment and therefore the use of the liquor in evidence vitiated the conviction. We granted the writ to determine this question. 333 U. S. 841.
The facts are substantially undisputed. At about six o’clock on the evening of March 3, 1947, Malsed, an investigator of the Alcohol Tax Unit, and Creehan, a special investigator, were parked in a car beside a highway near the Quapaw Bridge in northeastern Oklahoma. The point was about five miles west of the Missouri-Oklahoma line. Brinegar drove past headed west in his Ford coupe. Malsed had arrested him about five months earlier for illegally transporting liquor; had seen him loading liquor into a car or truck in Joplin, Missouri, on at least two occasions during the preceding six months; and knew him to have a reputation for hauling liquor. As Brinegar passed, Malsed recognized both him and the Ford. He told Creehan, who was driving the officers’ car, that Brinegar was the driver of the passing car. Both agents later testified that the car, but not especially its rear end, appeared to be “heavily loaded” and “weighted with something.” Brinegar increased his speed as he passed the officers. They gave chase. After pursuing him for about a mile at top speed, they gained on him as his car skidded on a curve, sounded their siren, overtook him, and crowded his car to the side of the road by pulling across in front of it. The highway was one leading from Joplin, Missouri, toward Vinita, Oklahoma, Brinegar’s home.
As the agents got out of their car and walked back toward petitioner, Malsed said, “Hello, Brinegar, how much liquor have you got in the car?” or “How much liquor have you got in the car this time?” Petitioner replied, “Not too much,” or “Not so much.” After further questioning he admitted that he had twelve cases in the car. Malsed testified that one case, which was on the front seat, was visible from outside the car, but petitioner testified that it was covered by a lap robe. Twelve more cases were found under and behind the front seat. The agents then placed Brinegar under arrest and seized the liquor.
The district judge, after a hearing on the motion to suppress at which the facts stated above appeared in evidence, was of the opinion that “the mere fact that the agents knew that this defendant was engaged in hauling whiskey, even coupled with the statement that the car appeared to be weighted, would not be probable cause for the search of this car.” Therefore, he thought, there was no probable cause when the agents began the chase. He held, however, that the voluntary admission made by petitioner after his car had been stopped constituted probable cause for a search, regardless of the legality of the arrest and detention, and that therefore the evidence was admissible. At the trial, as has been said, the court overruled petitioner’s renewal of the objection.
The Court of Appeals, one judge dissenting, took essentially the view held by the District Court. The dissenting judge thought that the search was unlawful and therefore statements made during its course could not justify the search.
The crucial question is whether there was probable cause for Brinegar’s arrest, in the light of prior adjudications on this problem, more particularly Carroll v. United States, 267 U. S. 132, which on its face most closely approximates the situation presented here.
The Carroll decision held that, under the Fourth Amendment, a valid search of a vehicle moving on a public highway may be had without a warrant, but only if probable cause for the search exists. The Court then went on to rule that the facts presented amounted to probable cause for the search of the automobile there involved. 267 U. S. 132,160.
In the Carroll case three federal prohibition agents and a state officer stopped and searched the defendants’ car on a highway leading from Detroit to Grand Rapids, Michigan, and seized a quantity of liquor discovered in the search. About three months before the search, the two defendants and another man called on two of the agents at an apartment in Grand Rapids and, unaware that they were dealing with federal agents, agreed to sell one of the agents three cases of liquor. Both agents noticed the Oldsmobile roadster in which the three men came to the apartment and its license number. Presumably because the official capacity of the proposed purchaser was suspected by the defendants, the liquor was never delivered.
About a week later the same two agents, while patrolling the road between Grand Rapids and Detroit on the lookout for violations of the National Prohibition Act, were passed by the defendants, who were proceeding in a direction from Grand Rapids toward Detroit in the same Oldsmobile roadster. The agents followed the defendants for some distance but lost trace of them. Still later, on the occasion of the search, while the officers were patrolling the same highway, they met and passed the defendants, who were in the same roadster, going in a direction from Detroit toward Grand Rapids. Recognizing the defendants, the agents turned around, pursued them, stopped them about sixteen miles outside Grand Rapids, searched their car and seized the liquor it carried.
This Court ruled that the information held by the agents, together with the judicially noticed fact that Detroit was “one of the most active centers for introducing illegally into this country spirituous liquors for distribution into the interior” (267 U. S. at 160), constituted probable cause for the search.
I.
Obviously the basic facts held to constitute probable cause in the Carroll case were very similar to the basic facts here. In each case the search was of an automobile moving on a public highway and was made without a warrant by federal officers charged with enforcing federal statutes outlawing the transportation of intoxicating liquors (except under conditions not complied with). In each instance the officers were patrolling the highway in the discharge of their duty. And in each before stopping the car or starting to pursue it they recognized both the driver and the car, from recent personal contact and observation, as having been lately engaged in illicit liquor dealings. Finally, each driver was proceeding in his identified car in a direction from a known source of liquor supply toward a probable illegal market, under circumstances indicating no other probable purpose than to carry on his illegal adventure.
These are the ultimate facts. Necessarily the concrete, subordinate facts on which they were grounded in the two cases differed somewhat in detail. The more important of the variations in details of the proof are as follows:
In Carroll the agent’s knowledge of the primary and ultimate fact that the accused were engaged in liquor running was derived from the defendants’ offer to sell liquor to the agents some three months prior to the search, while here that knowledge was derived largely from Malsed’s personal observation, reinforced by hearsay; the officers when they bargained for the liquor in Carroll saw the number of the defendants’ car, whereas no such fact is shown in this record; and in Carroll the Court took judicial notice that Detroit was on the international boundary and an active center for illegal importation of spirituous liquors for distribution into the interior, while in this case the facts that Joplin, Missouri, was a ready source of supply for liquor and Oklahoma a place of likely illegal market were known to the agent Malsed from his personal observation and experience as well as from facts of common knowledge.
Treating first the two latter and less important matters, in view of the positive and undisputed evidence concerning Malsed’s identification of Brinegar’s Ford, we think no significance whatever attaches, for purposes of distinguishing the cases, to the fact that in the Carroll case the officers saw and recalled the license number of the offending car while this record discloses no like recollection.
Likewise it is impossible to distinguish the Carroll case with reference to the proof relating to the source of supply, the place of probable destination and illegal market, and consequently the probability that the known liquor operators were using the connecting highway for the purposes of their unlawful business.
There were of course some legal as well as some factual differences in the two situations. Under the statute in review in Carroll the whole nation was legally dry. Not only the manufacture, but the importation, transportation and sale of intoxicating liquors were prohibited throughout the country. Under the statute now in question only the importation of such liquors contrary to the law of the state into which they are brought and in which they were seized is forbidden.
In the Carroll case the Court judicially noticed that Detroit was located on the international boundary with Canada and had become an active center for illegally bringing liquor into the country for distribution into the interior. This was pertinent in connection with other circumstances, for showing the probability under which the agents acted that use of the highway connecting Detroit and Grand Rapids by the known operators in liquor was for the purpose of carrying on their unlawful traffic.
In this case, the record shows that Brinegar had used Joplin, Missouri, to Malsed’s personal knowledge derived from direct observation, not merely from hearsay as seems to be suggested, as a source of supply on other occasions within the preceding six months. It also discloses that Brinegar’s home was in Vinita, Oklahoma, and that Brinegar when apprehended was traveling in a direction leading from Joplin to Vinita, at a point about four or five miles west of the Missouri-Oklahoma line.
Joplin, like Detroit in the Carroll case, was a ready source of supply. But unlike Detroit it was not an illegal source. So far as appears, Brinegar’s purchases there were entirely legal. And so, we may assume for present purposes, was his transportation of the liquor in Missouri, until he reached and crossed the state line into Oklahoma.
This difference, however, is insubstantial. For the important thing here is not whether Joplin was an illegal source of supply; it is rather that Joplin was a ready, convenient and probable one for persons disposed to violate the Oklahoma and federal statutes. That fact was demonstrated fully, not only by the geographic facts, but by Malsed’s direct and undisputed testimony of his personal observation of Brinegar’s use of liquor-dispensing establishments in Joplin for procuring his whiskey. Such direct evidence was lacking in Carroll as to Detroit, and for that reason the Court resorted to judicial notice of the commonly known facts to supply that deficiency. Malsed’s direct testimony, based on his personal observation, dispensed with that necessity in this case.
The situation relating to the probable place of market, as bearing on the probability of unlawful importation, is somewhat different. Broadly on the facts this may well have been taken to be the State of Oklahoma as a whole or its populous northeastern region. From the facts of record we know, as the agents knew, that Oklahoma was a “dry” state. At the time of the search, its law forbade the importation of intoxicating liquors from other states, except under a permit not generally procurable and which there is no pretense Brinegar had secured or attempted to secure. This fact, taken in connection with the known “wet” status of Missouri and the location of Joplin close to the Oklahoma line, affords a very natural situation for persons inclined to violate the Oklahoma and federal statutes to ply their trade. The proof therefore concerning the source of supply, the place of probable destination and illegal market, and hence the probability that Brinegar was using the highway for the forbidden transportation, was certainly no less strong than the showing in these respects in the Carroll case.
Finally, as for the most important potential distinction, namely, that concerning the primary and ultimate fact that the petitioner was engaging in liquor running, Malsed’s personal observation of Brinegar’s recent activities established that he was so engaged quite as effectively as did the agent’s prior bargaining with the defendants in the Carroll case. He saw Brinegar loading liquor, in larger quantities than would be normal for personal consumption, into a car or a truck in Joplin on other occasions during the six months prior to the search. He saw the car Brinegar was using in this case in use by him at least once in Joplin within that period and followed it. And several months prior to the search he had arrested Brine-gar for unlawful transportation of liquor and this arrest had resulted in an indictment which was pending at the time of this trial. Moreover Malsed instantly recognized Brinegar’s Ford coupe and Brinegar as the driver when he passed the parked police car. And at that time Brinegar was moving in a direction from Joplin toward Vinita only a short distance inside Oklahoma from the state line.
All these facts are undisputed. Wholly apart from Malsed’s knowledge that Brinegar bore the general reputation of being engaged in liquor running, they constitute positive and convincing evidence that Brinegar was engaged in that activity, no less convincing than the evidence in Carroll that the defendants had offered to sell liquor to the officers. The evidence here is undisputed, is admissible on the issue of probable cause, and clearly establishes that the agent had good ground for believing that Brinegar was engaged regularly throughout the period in illicit liquor running and dealing.
Notwithstanding the variations in detail, therefore, we think the proof in this case furnishes support quite as strong as that made in the Carroll case, indeed stronger in some respects, to sustain the ultimate facts there held in the aggregate to constitute probable cause for a search identical in all substantial and material respects with the one made here. Nothing in the variations of detail affords a substantial basis for undermining here any of the ultimate facts held to be sufficient in Carroll or for distinguishing the cases. Each of the ultimate facts found in Carroll to constitute probable cause, when taken together, is present in this case and is fully substantiated by the proof. Accordingly the Carroll decision must be taken to control this situation, unless it is now to be overruled.
This is true, although the trial court and the Court of Appeals, including the dissenting judge, were of the opinion, as stated by the latter court, “that the facts within the knowledge of the investigators and of which they had reasonable trustworthy information prior to the time the incriminating statements were made by Brinegar were not sufficient to lead a reasonably discreet and prudent man to believe that intoxicating liquor was being transported in the coupe, and did not constitute probable cause for a search.” 165 F. 2d at 514. If, as we think, the Carroll case is indistinguishable from this one on the material facts, and that decision is to continue in force, it necessarily follows that the quoted “finding” or “conclusion” was erroneous. In the absence of any significant difference in the facts, it cannot be that the Fourth Amendment’s incidence turns on whether different trial judges draw general conclusions that the facts are sufficient or insufficient to constitute probable cause.
II.
It remains to consider one further asserted difference between this case and the Carroll case, having to do with the admissibility or inadmissibility at the trial of the evidence on which the agents acted in making the search, particularly the evidence concerning their knowledge that the defendants were engaging in illicit liquor running.
It is argued first that this case can be distinguished from Carroll because Malsed’s knowledge of this primary and ultimate fact rested wholly or largely on surmise or hearsay. This argument is disproved by the facts of record which we have set forth above. There was hearsay, but there was much more. Indeed, as we have emphasized, the facts derived from Malsed’s personal observations were sufficient in themselves, without the hearsay concerning general reputation, to sustain his conclusion concerning the illegal character of Brinegar’s operations.
But a further distinction based upon inadmissibility of the evidence is asserted. It is said that, while in Carroll the defendants’ offer to sell .liquor to the agents was admissible and was admitted at the trial, here the evidence that Malsed had arrested Brinegar for illegal transportation of liquor several months before the search, though admitted on the hearing on the motion to suppress, was excluded at the trial. Cf. Michelson v. United States, 335 U. S. 469. The inference seems to be that the evidence concerning the prior arrest should not have been received at the hearing on the motion. In any event, the conclusion is drawn that the factors relating to inadmissibility of the evidence here, for purposes of proving guilt at the trial, deprive the evidence as a whole of sufficiency to show probable cause for the search and therefore distinguish this case from the Carroll case.
Apart from its failure to take account of the facts disclosed by Malsed’s direct and personal observation, even if his testimony concerning the prior arrest were excluded, the so-called distinction places a wholly unwarranted emphasis upon the criterion of admissibility in evidence, to prove the accused’s guilt, of the facts relied upon to show probable cause. That emphasis, we think, goes much too far in confusing and disregarding the difference between what is required to prove guilt in a criminal case and what is required to show probable cause for arrest or search. It approaches requiring (if it does not in practical effect require) proof sufficient to establish guilt in order to substantiate the existence of probable cause. There is a large difference between the two things to be proved, as well as between the tribunals which determine them, and therefore a like difference in the quanta and modes of proof required to establish them.
For a variety of reasons relating not only to probative value and trustworthiness, but also to possible prejudicial effect upon a trial jury and the absence of opportunity for cross-examination, the generally accepted rules of evidence throw many exclusionary protections about one who is charged with and standing trial for crime. Much evidence of real and substantial probative value goes out on considerations irrelevant to its probative weight but relevant to possible misunderstanding or misuse by the jury.
Thus, in this case, the trial court properly excluded from the record at the trial, cf. Michelson v. United States, 335 U. S. 469, Malsed’s testimony that he had arrested Brinegar several months earlier for illegal transportation of liquor and that the resulting indictment was pending in another court at the time of the trial of this case. This certainly was not done on the basis that the testimony concerning arrest, or perhaps even the indictment, was surmise or hearsay or that it was without probative value. Yet the same court admitted the testimony at the hearing on the motion to suppress the evidence seized in the search, where the issue was not guilt but probable cause and was determined by the court without a jury.
The court’s rulings, one admitting, the other excluding the identical testimony, were neither inconsistent nor improper. They illustrate the difference in standards and latitude allowed in passing upon the distinct issues of probable cause and guilt. Guilt in a criminal case must be proved beyond a reasonable doubt and by evidence confined to that which long experience in the common-law tradition, to some extent embodied in the Constitution, has crystallized into rules of evidence consistent with that standard. These rules are historically grounded rights of our system, developed to safeguard men from dubious and unjust convictions, with resulting forfeitures of life, liberty and property.
However, if those standards were to be made applicable in determining probable cause for an arrest or for search and seizure, more especially in cases such as this involving moving vehicles used in the commission of crime, few indeed would be the situations in which an officer, charged with protecting the public interest by enforcing the law, could take effective action toward that end. Those standards have seldom been so applied.
In dealing with probable cause, however, as the very name implies, we deal with probabilities. These are not technical; they are the factual and practical considerations of everyday life on which reasonable and prudent men, not legal technicians, act. The standard of proof is accordingly correlative to what must be proved.
“The substance of all the definitions” of probable cause “is a reasonable ground for belief of guilt.” McCarthy v. De Armit, 99 Pa. St. 63, 69, quoted with approval in the Carroll opinion. 267 U. S. at 161. And this “means less than evidence which would justify condemnation” or conviction, as Marshall, C. J., said for the Court more than a century ago in Locke v. United States, 7 Cranch 339, 348. Since Marshall’s time, at any rate, it has come to mean more than bare suspicion: Probable cause exists where “the facts and circumstances within their [the officers’] knowledge and of which they had reasonably trustworthy information [are] sufficient in themselves to warrant a man of reasonable caution in the belief that” an offense has been or is being committed. Carroll v. United States, 267 U. S. 132, 162.
These long-prevailing standards seek to safeguard citizens from rash and unreasonable interferences with privacy and from unfounded charges of crime. They also seek to give fair leeway for enforcing the law in the community’s protection. Because many situations which confront officers in the course of executing their duties are more or less ambiguous, room must be allowed for some mistakes on their part. But the mistakes must be those of reasonable men, acting on facts leading sensibly to their conclusions of probability. The rule of probable cause is a practical, nontechnical conception affording the best compromise that has been found for accommodating these often opposing interests. Requiring more would unduly hamper law enforcement. To allow less would be to leave law-abiding citizens at the mercy of the officers’ whim or caprice.
The troublesome line posed by the facts in the Carroll case and this case is one between mere suspicion and probable cause. That line necessarily must be drawn by an act of judgment formed in the light of the particular situation and with account taken of all the circumstances. No problem of searching the home or any other place of privacy was presented either in Carroll or here. Both cases involve freedom to use public highways in swiftly moving vehicles for dealing in contraband, and to be unmolested by investigation and search in those movements. In such a case the citizen who has given no good cause for believing he is engaged in that sort of activity is entitled to proceed on his way without interference. But one who recently and repeatedly has given substantial ground for believing that he is engaging in the forbidden transportation in the area of his usual operations has no such immunity, if the officer who intercepts him in that region knows that fact at the time he makes the interception and the circumstances under which it is made are not such as to indicate the suspect is going about legitimate affairs.
This does not mean, as seems to be assumed, that every traveler along the public highways may be stopped and searched at the officers’ whim., caprice or mere suspicion. The question presented in the Carroll case lay on the border between suspicion and probable cause. But the Court carefully considered that problem and resolved it by concluding that the facts within the officers’ knowledge when they intercepted the Carroll defendants amounted to more than mere suspicion and constituted probable cause for their action. We cannot say this conclusion was wrong, or was so lacking in reason and consistency with the Fourth Amendment’s purposes that it should now be overridden. Nor, as we have said, can we find in the present facts any substantial basis for distinguishing this case from the Carroll case.
Accordingly the judgment is
Affirmed.
Section 3 (a) of the Liquor Enforcement Act of 1936, 49 Stat. 1928, 27 U. S, C. §223, provides: “Whoever shall import, bring, or transport any intoxicating liquor into any State in which all sales (except for scientific, sacramental, medicinal, or mechanical purposes) of intoxicating liquor containing more than 4 per centum of alcohol by volume are prohibited, otherwise than in the course of continuous interstate transportation through such State, or attempt so to do, or assist in so doing, shall: (1) If such liquor is not accompanied by such permit or permits, license or licenses therefor as are now or hereafter required by the laws of such State; or (2) if all importation, bringing, or transportation of intoxicating liquor into such State is prohibited by the laws thereof; be guilty of a misdemeanor and shall be fined not more than $1,000 or imprisoned not more than one year, or both.” Okla. Sess. Laws, 1939, c. 16, Art. 1, § 1, in effect at the time of petitioner’s arrest, made it unlawful to import or cause to be imported into that state, without a permit, any intoxicating liquor containing more than 4 per cent of alcohol by volume.
“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, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.” U. S. Const. Amend. IV.
Neither the opinion of the Court of Appeals nor the unpublished opinion of the trial court refers to the Carroll case.
“The Fourth Amendment does not denounce all searches or seizures, but only such as are unreasonable. ... On reason and authority the true rule is that if the search and seizure without a warrant are made upon probable cause, that is, upon a belief, reasonably arising out of circumstances known to the seizing officer, that an automobile or other vehicle contains that which by law is subject to seizure and destruction, the search and seizure are valid.” Carroll v. United States, 267 U. S. 132, 147, 149.
The substantive offense charged in Carroll was violation of the National Prohibition Act, 41 Stat. 305; here, violation of the Liquor Enforcement Act of 1936.
In this case identification of the car as having been previously used by Brinegar in his liquor-running activities was inferential, although identification of its use by him in Joplin, Mo., his source of supply, was direct and undisputed.
The Government also stresses the fact, not present in the Carroll case, of flight by Brinegar after he realized he was being pursued. We find it is unnecessary to take account of this factor in deciding this case. As to the factor of flight, see Husty v. United States, 282 U. S. 694, 700-701; Talley v. United States, 159 F. 2d 703; United States v. Heitner, 149 F. 2d 105, 107; Jones v. United States, 131 F. 2d 539, 541; Levine v. United States, 138 F. 2d 627, 629.
It was unlawful to import into Oklahoma, without a permit, any intoxicating liquor, as defined by the laws of that state, containing more than four per cent of alcohol by volume. See note 1 supra. Manufacture, sale, furnishing or transportation of intoxicating liquor was forbidden in Oklahoma. 37 Okla. Stat. § 1 (1941).
Indeed the showing here was stronger because there was no necessity, as there was in the Carroll case, for resorting to judicial notice to establish either the probable source of supply or that it was illegal. On the present record judicial notice is hardly needed to give us cognizance of the differing laws of Missouri and Oklahoma, or of Joplin’s proximity to the state line, and its ready convenience to one living as near by as Vinita who might be disposed to use it as a base of supply for importing liquor into Oklahoma in violation of the state and federal statutes.
As has been noted above, the Carroll case is neither cited nor referred to in any of the opinions filed in the trial court and the Court of Appeals. Nor is there anything in the record before us showing that the Carroll decision was considered in any of the rulings made in the hearing on the motion to suppress, at the trial, or in the Court of Appeals.
The court however thought that, even with the fact of the arrest before it, the evidence was insufficient to show probable cause at the time Brinegar passed the police car.
The inappropriateness of applying the rules of evidence as a criterion to determine probable cause is apparent in the case of an application for a warrant before a magistrate, the context in which the issue of probable cause most frequently arises. The ordinary rules of evidence are generally not applied in ex parte proceedings, “partly because there is no opponent to invoke them, partly because the judge’s determination is usually discretionary, partly because it is seldom final, but mainly because the system of Evidence rules was devised for the special control of trials by jury.” 1 Wigmore, Evidence (3d ed., 1940) 19. See also Note, 46 Harv. L. Rev. 1307, 1310-1311.
But see, e. g., Grau v. United States, 287 U. S. 124, 128, in which it was said by way of dictum that “A search warrant may issue only upon evidence which would be competent in the trial of the offense before a jury (Giles v. United States, 284 Fed. 208; Wagner v. United States, 8 F. (2d) 581 . . . .” For this proposition there was no authority in the decisions of this Court. It was stated in a case in which the evidence adduced to prove probable cause was not incompetent, but was insufficient to support the inference necessary to the existence of probable cause. The statement has not been repeated by this Court.
The Wagner case relies solely upon Giles, the other case cited in Grau, and holds a warrant bad which issued on the basis of “hearsay and conclusions.” The Grau dictum occasionally has been applied or stated as dictum by the courts of appeals and district courts: Simmons v. United States, 18 F. 2d 85, 88; Worthington v. United States, 166 F. 2d 557, 564-565; see also Reeve v. Howe, 33 F. Supp. 619, 622; United States v. Novero, 58 F. Supp. 275, 279. Cf. Davis v. United States, 35 F. 2d 957. See Note, 46 Harv. L. Rev. 1307, 1310-1311, for a criticism of the Grau dictum. And see note 15, infra, and text.
Marshall’s full statement in Locke v. United States was: “It may be added, that the term ‘probable cause,’ according to its usual acceptation, means less than evidence which would justify condemnation ; and, in all cases of seizure, has a fixed and well known meaning. It imports a seizure made under circumstances which warrant suspicion.” 7 Cranch 339, 348.
To the same effect are: Husty v. United States, 282 U. S. 694, 700-701; Dumbra v. United States, 268 U. S. 435, 441; Steele v. United States No. 1, 267 U. S. 498, 504-505; Stacey v. Emery, 97 U. S. 642, 645.
The Carroll opinion also quotes with approval the following statement: “If the facts and circumstances before the officer are such as to warrant a man of prudence and caution in believing that the offense has been committed, it is sufficient.” P. 161. Ascription of the statement to Locke v. United States, 7 Cranch 339, appears to be an error in citation.
See the discussion of exceptions in the Carroll opinion, 267 U. S. 132, 149 ff.
“It would be intolerable and unreasonable if a prohibition agent were authorized to stop every automobile on the chance of finding liquor and thus subject all persons lawfully using the highways to the inconvenience and indignity of such a search. Travellers may be so stopped in crossing an international boundary because of national self protection reasonably requiring one entering the country to identify himself as entitled to come in, and his belongings as effects which may be lawfully brought in. But those lawfully within the country, entitled to use the public highways, have a right to free passage without interruption or search unless there is known to a competent official authorized to search, probable cause for believing that their vehicles are carrying contraband or illegal merchandise.” Carroll v. United States, 267 U. S. 132, 153-154.