opinion: Mr. Justice White
  delivered the opinion of the Court.
  The principal question in this case concerns the admissibility of evidence seized from an automobile, in which petitioner was riding at the time of his arrest, after the automobile was taken to a police station and was there thoroughly searched without a warrant. The Court of Appeals for the Third Circuit found no violation of petitioner’s Fourth Amendment rights. We affirm.
  I
  During the night of May 20, 1963, a Gulf service station in North Braddock, Pennsylvania, was robbed by two men, each of whom carried and displayed a gun. The robbers took the currency from the cash register; the service station attendant, one Stephen Kovacich, was directed to place the coins in his right-hand glove, which was then taken by the robbers. Two teen-agers, who had earlier noticed a blue compact station wagon circling the block in the vicinity of the Gulf station, then saw the station wagon speed away from a parking lot close to the Gulf station. About the same time, they learned that the Gulf station had been robbed. They reported to police, who arrived immediately, that four men were in the station wagon and one was wearing a green sweater. Kova-cich told the police that one of the men who robbed him was wearing a green sweater and the other was wearing a trench coat. A description of the car and the two robbers was broadcast over the police radio. Within an hour, a light blue compact station wagon answering the description and carrying four men was stopped by the police about two miles from the Gulf station. Petitioner was one of the men in the station wagon. He was wearing a green sweater and there was a trench coat in the car. The occupants were arrested and the car was driven to the police station. In the course of a thorough search of the car at the station, the police found concealed in a compartment under the dashboard two .38-caliber revolvers (one loaded with dumdum bullets), a right-hand glove containing small change, and certain cards bearing the name of Raymond Havicon, the attendant at a Boron service station in McKeesport, Pennsylvania, who had been robbed at gunpoint on May 13, 1963. In the course of a warrant-authorized search of petitioner’s home the day after petitioner’s arrest, police found and seized certain .38-caliber ammunition, including some dumdum bullets similar' to those found in one of the guns taken from the station wagon.
  Petitioner was indicted for both robberies. His first trial ended in a mistrial but he was convicted of both robberies at the second trial. Both Kovacieh and Hav-icon identified petitioner as one of the robbers. The materials taken from the station wagon were introduced into evidence, Kovacieh identifying his glove and Hav-icon the cards taken in the May 13 robbery. The bullets seized at petitioner’s house were also introduced over objections of petitioner’s counsel. Petitioner was sentenced to a term of four to eight years’ imprisonment for the May 13 robbery and to a term of two to seven years’ imprisonment for the May 20 robbery, the sentences to run consecutively. Petitioner did not take a direct appeal from these convictions. In 1965, petitioner sought a writ of habeas corpus in the state court, which denied the writ after a brief evidentiary hearing; the denial of the writ was affirmed on appeal in the Pennsylvania appellate courts. Habeas corpus proceedings were then commenced in the United States District Court for the Western District of Pennsylvania. An order to show cause was issued. Based on the State’s response and the state court record, the petition for habeas corpus was denied without a hearing. The Court of Appeals for the Third Circuit affirmed, 408 F. 2d 1186, and we granted certiorari, 396 U. S. 900 (1969).
  II
  We pass quickly the claim that the search of the automobile was the fruit of an unlawful arrest. Both the courts below thought the arresting officers had probable cause to make the arrest. We agree. Having talked to the teen-age observers and to the victim Kova-cich, the police had ample cause to stop a light blue compact station wagon carrying four men and to arrest the occupants, one of whom was wearing a green sweater and one of whom had a trench coat with him in the car.
  Even so, the search that produced the incriminating evidence was made at the police station some time after the arrest and cannot be justified as a search incident to an arrest: “Once an accused is under arrest and in custody, then a search made at another place, without a warrant, is simply not incident to the arrest.” Preston v. United States, 376 U. S. 364, 367 (1964). Dyke v. Taylor Implement Mfg. Co., 391 U. S. 216 (1968), is to the same effect; the reasons that have been thought sufficient to justify warrantless searches carried out in connection with an. arrest no longer obtain when the accused is safely in custody at the station house.
  There are, however, alternative grounds arguably justifying the search of the car in this case. In Preston, supra, the arrest was for vagrancy; it was apparent that the officers had no cause to believe that evidence of crime was concealed in the auto. In Dyke, supra, the Court expressly rejected the suggestion that there was probable cause to search the car, 391 U. S., at 221-222. Here the situation is different, for the police had probable cause to believe that the robbers, carrying guns and the fruits of the crime, had fled the scene in a light blue compact station wagon which would be carrying four men, one wearing a green sweater and another wearing a trench coat. As the state courts correctly held, there was probable cause to arrest the occupants of the station wagon that the officers stopped; just as obviously was there probable cause to search the car for guns and stolen money.
  In terms of the circumstances justifying a warrantless search, the Court has long distinguished between an automobile and a home or office. In Carroll v. United States, 267 U. S. 132 (1925), the issue was the admissibility in evidence of contraband liquor seized in a war-rantless search of a car on the highway. After surveying the law from the time of the adoption of the Fourth Amendment onward, the Court held that automobiles and other conveyances may be searched without a warrant in circumstances that would not justify the search without a warrant of a house or an office, provided that there is probable cause to believe that the car contains articles that the officers are entitled to seize. The Court expressed its holding as follows:
  “We have made a somewhat extended reference to these statutes to show that the guaranty of freedom from unreasonable searches and seizures by the Fourth Amendment has been construed, practically since the beginning of the Government, as recognizing a necessary difference between a search of a store, dwelling house or other structure in respect of which a proper official warrant readily may be obtained, and a search of a ship, motor boat, wagon or automobile, for contraband goods, where it is not practicable to secure a warrant because the vehicle can be quickly moved out of the locality or jurisdiction in which the warrant must be sought.
  “Having thus established that contraband goods concealed and illegally transported in an automobile or other vehicle may be searched for without a warrant, we come now to consider under what circumstances such search may be made. . . . [T]hose 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. . . .
  “The measure of legality of such a seizure is, therefore, that the seizing officer shall have reasonable or probable cause for believing that the automobile which he stops and seizes has contraband liquor therein which is being illegally transported.” 267 U. S., at 153-154, 155-156.
  The Court also noted that the search of an auto on probable cause proceeds on a theory wholly different from that justifying the search incident to an arrest:
  “The right to search and the validity of the seizure are not dependent on the right to arrest. They are dependent on the reasonable cause the seizing officer has for belief that the contents of the automobile offend against the law.” 267 U. S., at 158-159.
  Finding that there was probable cause for the search and seizure at issue before it, the Court affirmed the convictions.
  Carroll was followed and applied in Husty v. United States, 282 U. S. 694 (1931), and Scher v. United States, 305 U. S. 251 (1938). It was reaffirmed and followed in Brinegar v. United States, 338 U. S. 160 (1949). In 1964, the opinion in Preston, supra, cited both Brinegar and Carroll with approval, 376 U. S., at 366-367. In Cooper v. California, 386 U. S. 58 (1967), the Court read Preston as dealing primarily with a search incident to arrest and cited that case for the proposition that the mobility of a car may make the search of a car without a warrant reasonable “although the result might be the opposite in a search of a home, a store, or other fixed piece of property.” 386 U. S., at 59. The Court’s opinion in Dyke, 391 U. S., at 221, recognized that “[a]utomobiles, because of their mobility, may be searched without a warrant upon facts not justifying a warrantless search of a residence or office,” citing Brinegar and Carroll, supra. However, because there was insufficient reason to search the car involved in the Dyke case, the Court did not reach the question of whether those cases “extend to a warrant-less search, based upon probable cause, of an automobile which, having been stopped originally on a highway, is parked outside a courthouse.” 391 U. S., at 222.
  Neither Carroll, supra, nor other cases in this Court require or suggest that in every conceivable circumstance the search of an auto even with probable cause may be made without the extra protection for privacy that a warrant affords. But the circumstances that furnish probable cause to search a particular auto for particular articles are most often unforeseeable; moreover, the opportunity to search is fleeting since a car is readily movable. Where this is true, as in Carroll and the case before us now, if an effective search is to be made at any time, either the search must be made immediately without a warrant or the car itself must be seized and held without a warrant for whatever period is necessary to obtain a warrant for the search.
  In enforcing the Fourth Amendment’s prohibition against unreasonable searches and seizures, the Court has insisted upon probable cause as a minimum requirement for a reasonable search permitted by the Constitution. As a general rule, it has also required the judgment of a magistrate on the probable-cause issue and the issuance of a warrant before a search is made. Only in exigent circumstances will the judgment of the police as to probable cause serve as a sufficient authorization for a search. Carroll, supra, holds a search warrant unnecessary where there is probable cause to search an automobile stopped on the highway; the car is movable, the occupants are alerted, and the car’s contents may never be found again if a warrant must be obtained. Hence an immediate search is constitutionally permissible.
  Arguably, because of the preference for a magistrate’s judgment, only the immobilization of the car should be permitted until a search warrant is obtained; arguably, only the “lesser” intrusion is permissible until the magistrate authorizes the “greater.” But which is the “greater” and which the “lesser” intrusion is itself a debatable question and the answer may depend on a variety of circumstances. For constitutional purposes, we see no difference between on the one hand seizing and holding a car before presenting the probable cause issue to a magistrate and on the other hand carrying out an immediate search without a warrant. Given probable cause to search, either course is reasonable under the Fourth Amendment.
  On the facts before us, the blue station wagon could have been searched on the spot when it was stopped since there was probable cause to search and it was a fleeting target for a search. The probable-cause factor still obtained at the station house and so did the mobility of the car unless the Fourth Amendment permits a warrantless seizure of the car and the denial of its use to anyone until a warrant is secured. In that event there is little to choose in terms of practical consequences between an immediate search without a warrant and the car’s immobilization until a warrant i's obtained. The same consequences may not follow where there is unforeseeable cause to search a house. Compare Vale v. Louisiana, ante, p. 30. But as Carroll, supra, held, for the purposes of the Fourth Amendment there is a constitutional difference between houses and cars.
  Ill
  Neither of petitioner’s remaining contentions warrants reversal of the judgment of the Court of Appeals. One of them challenges the admissibility at trial of the .38-caliber ammunition seized in the course of a search of petitioner’s house. The circumstances relevant to this issue are somewhat confused, involving as they do questions of probable cause, a lost search warrant, and the Pennsylvania procedure for challenging the admissibility of evidence seized. Both the District Court and the Court of Appeals, however, after careful examination of the record, found that if there was error in admitting the ammunition, the error was harmless beyond a reasonable doubt. Having ourselves studied this record, we are not prepared to differ with the two courts below. See Harrington v. California, 395 U. S. 250 (1969).
  The final claim is that petitioner was not afforded the effective assistance of counsel. The facts pertinent to this claim are these: The Legal Aid Society of Allegheny County was appointed to represent petitioner prior to his first trial. A representative of the society conferred with petitioner, and a member of its staff, Mr. Middleman, appeared for petitioner at the first trial. There is no claim that petitioner was not then adequately represented by fully prepared counsel. The difficulty arises out of the second trial. Apparently no one from the Legal Aid Society again conferred with petitioner until a few minutes before the second trial began. The attorney who then appeared to represent petitioner was not Mr. Middleman but Mr. Tamburo, another Legal Aid Society attorney. No charge is made that Mr. Tamburo was incompetent or inexperienced; rather the claim is that his appearance for petitioner was so belated that he could not have furnished effective legal assistance at the second trial. Without granting an evidentiary hearing, the District Court rejected petitioner’s claim. The Court of Appeals dealt with the matter in an extensive opinion. After carefully examining the state court record, which it had before it, the court found ample grounds for holding that the appearance of a different attorney at the second trial had not resulted in prejudice to petitioner. The claim that Mr. Tamburo was unprepared centered around his allegedly inadequate efforts to have the guns and ammunition excluded from evidence. But the Court of Appeals found harmless any error in the admission of the bullets and ruled that the guns and other materials seized from the car were admissible evidence. Hence the claim of prejudice from the substitution of counsel was without substantial basis. In this posture of the case we are not inclined to disturb the judgment of the Court of Appeals as to what the state record shows with respect to the adequacy of counsel. Unquestionably, the courts should make every effort to effect early appointments of counsel in all cases. But we are not disposed to fashion a per se rule requiring reversal of every conviction following tardy appointment of counsel or to hold that, whenever a habeas corpus petition alleges a belated appointment, an evidentiary hearing must be held to determine whether the defendant has been denied his constitutional right to counsel. The Court of Appeals reached the right result in denying a hearing in this case.
  Affirmed.
  Mr. Justice Blackmun took no part in the consideration or decision of this case.
  Petitioner was indicted separately for each robbery. One of the other three men was similarly indicted and the other two were indicted only for the Gulf robbery. All indictments and all defendants were tried together. In a second trial following a mistrial, the jury found all defendants guilty as charged.
  Kovacieh identified petitioner at a pretrial stage of the proceedings, and so testified, but could not identify him at the trial. Havieon identified petitioner both before trial and at trial.
  The bullets were apparently excluded at the first trial. The grounds for the exclusion do not clearly appear from the record now before us.
  The four-to-eight-year sentence was to be served concurrently with another sentence, for an unrelated armed robbery offense, imposed earlier but vacated subsequent to imposition of sentence in this case. The two-to-seven-year term was to be consecutive to the other sentences. It appears that the offenses here at issue caused revocation of petitioner’s parole in connection with a prior conviction. Apparently petitioner has now begun to serve the first of the two sentences imposed for the convictions here challenged.
  Since Mapp v. Ohio, 367 U. S. 643 (1961), the federal courts have regularly entertained and ruled on petitions for habeas corpus filed by state prisoners alleging that unconstitutionally seized evidence was admitted at their trials. See, e. g., Mancusi v. DeForte, 392 U. S. 364 (1968); Carafas v. LaVallee, 391 U. S. 234 (1968); Warden v. Hayden, 387 U. S. 294 (1967). As for federal prisoners, a divided Court held that relief under 28 U. S. C. § 2255 was available to vindicate Fourth Amendment rights. Kaufman v. United States, 394 U. S. 217 (1969). Right-to-counsel claims of course have regularly been pressed and entertained in federal habeas corpus proceedings.
  It is relevant to note here that petitioner Chambers at trial made no objection to the introduction of the items seized from the car; however his Fourth Amendment claims with respect to the auto search were raised and passed on by the Pennsylvania courts in the state habeas corpus proceeding. His objection to the search of his house was raised at his trial and rejected both on the merits and because he had not filed a motion to suppress; similar treatment was given the point in the state collateral proceedings, which took place before the same judge who had tried the criminal case. The counsel claim was not presented at trial but was raised and rejected in the state collateral proceedings.
  In any event, as we point out below, the validity of an arrest is not necessarily determinative of the right to search a car if there is probable cause to make the search. Here, as will be true in many cases, the circumstances justifying the arrest are also those furnishing probable cause for the search.
  Cooper involved the warrantless search of a car held for forfeiture under state law. Evidence seized from the car in that search was held admissible. In the case before us no claim is made that state law authorized that the station wagon be held as evidence or as an instrumentality of the crime; nor was the station wagon an abandoned or stolen vehicle. The question here is whether probable cause justifies a warrantless search in. the circumstances presented.
  Nothing said last term in Chimel v. California, 395 U. S. 752 (1969), purported to modify or affect the rationale of Carroll. As the Court noted:
  “Our holding today is of course entirely consistent with the recognized principle that, assuming the existence of probable cause, automobiles and other vehicles may be searched without warrants 'where it is not practicable to secure a warrant because the vehicle can be quickly moved out of the locality or jurisdiction in which the warrant must be sought.’ Carroll v. United States, 267 U. S. 132, 153; see Brinegar v. United States, 338 U. S. 160.” 395 U. S., at 764 n. 9.
  Following the car until a warrant can be obtained seems an impractical alternative since, among other things, the car may be taken out of the jurisdiction. Tracing the car and searching it hours or days later would of course permit instruments or fruits of crime to be removed from the car before the search.
  It was not unreasonable in this case to take the car to the station house. All occupants in the car were arrested in a dark parking lot in the middle of the night. A careful search at that point was impractical and perhaps not safe for the officers, and it would serve the owner’s convenience and the safety of his car to have the vehicle and the keys together at the station house.
  It is pertinent to note that each of the four defendants was represented by separate counsel. The attorney for Lawson, who was the car owner and who was the only defendant to take the stand, appears to have been the lead counsel. As far as the record before us reveals, no counsel made any objection at the trial to the admission of the items taken from the car. Petitioner’s counsel objected to the introduction of the bullets seized from petitioner’s house.
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