opinion: Justice Scalia delivered
  the opinion of the Court.
  In United States v. Matlock, 415 U. S. 164 (1974), this Court reaffirmed that a warrantless entry and search by law enforcement officers does not violate the Fourth Amendment’s proscription of “unreasonable searches and seizures” if the officers have obtained the consent of a third party who possesses common authority over the premises. The present case presents an issue we expressly reserved in Matlock, see id., at 177, n. 14: Whether a warrantless entry is valid when based upon the consent of a third party whom the police, at the time of the entry, reasonably believe to possess common authority over the premises, but who in fact does not do so.
  I
  Respondent Edward Rodriguez was arrested in his apartment by law. enforcement officers and charged with possession of illegal drugs. The police gained entry to the apartment with the consent and assistance of Gail Fischer, who had lived there with respondent for several months. The relevant facts leading to the arrest are as follows.
  On July 26, 1985, police were summoned to the residence of Dorothy Jackson on South Wolcott in Chicago. They were met by Ms. Jackson’s daughter, Gail Fischer, who showed signs of a severe beating. She told the officers that she had been assaulted by respondent Edward Rodriguez earlier that day in an apartment on South California Avenue. Fischer stated that Rodriguez was then asleep in the apartment, and she consented to travel there with the police in order to unlock the door with her key so that the officers could enter and arrest him. During this conversation, Fischer several times referred to the apartment on South California as “our” apartment, and said that she had clothes and furniture there. It is unclear whether she indicated that she currently lived at the apartment, or only that she used to live there.
  The police officers drove to the apartment on South California, accompanied by Fischer. They did not obtain an arrest warrant for Rodriguez, nor did they seek a search warrant for the apartment. At the apartment, Fischer unlocked the door with her key and gave the officers permission to enter. They moved through the door into the living room, where they observed in plain view drug paraphernalia and containers filled with white powder that they believed (correctly, as later analysis showed) to be cocaine. They proceeded to the bedroom, where they found Rodriguez asleep and discovered additional containers of white powder in two open attaché cases. The officers arrested Rodriguez and seized the drugs and related paraphernalia.
  Rodriguez was charged with possession of a controlled substance with intent to deliver. He moved to suppress all evidence seized at the time of his arrest, claiming that Fischer had vacated the apartment several weeks earlier and had no authority to consent to the entry. The Cook County Circuit Court granted the motion, holding that at the time she consented to the entry Fischer did not have common authority over the apartment. The Court concluded that Fischer was not a “usual resident” but rather an “infrequent visitor” at the apartment on South California, based upon its findings that Fischer’s name was not on the lease, that she did not contribute to the rent, that she was not allowed to invite others to the apartment on her own, that she did not have access to the apartment when respondent was away, and that she had moved some of her possessions from the apartment. The Circuit Court also rejected the State’s contention that, even if Fischer did not possess common authority over the premises, there was no Fourth Amendment violation if the police reasonably believed at the time of their entry that Fischer possessed the authority to consent.
  The Appellate Court of Illinois affirmed the Circuit Court in all respects. The Illinois Supreme Court denied the State’s petition for leave to appeal, 125 Ill. 2d 572, 537 N. E. 2d 816 (1989), and we granted certiorari. 493 U. S. 932 (1989).
  II
  The Fourth Amendment generally prohibits the warrant-less entry of a person’s home, whether to make an arrest or to search for specific objects. Payton v. New York, 445 U. S. 573 (1980); Johnson v. United States, 333 U. S. 10 (1948). The prohibition does not apply, however, to situations in which voluntary consent has been obtained, either from the individual whose property is searched, see Schneckloth v. Bustamonte, 412 U. S. 218 (1973), or from a third party who possesses common authority over the premises, see United States v. Matlock, supra, at 171. The State of Illinois contends that that exception applies in the present case.
  As we stated in Matlock, supra, at 171, n. 7, “[cjommon authority” rests “on mutual use of the property by persons generally having joint access or control for most purposes . . . .” The burden of establishing that common authority rests upon the State. On the basis of this record, it is clear that burden was not sustained. The evidence showed that although Fischer, with her two small children, had lived with Rodriguez beginning in December 1984, she had moved out on July 1, 1985, almost a month before the search at issue here, and had gone to live with her mother. She took her and her children’s clothing with her, though leaving behind some furniture and household effects. During the period after July 1 she sometimes spent the night at Rodriguez’s apartment, but never invited her friends there, and never went there herself when he was not home. Her name was not on the lease nor did she contribute to the rent. She had a key to the apartment, which she said at trial she had taken without Rodriguez’s knowledge (though she testified at the preliminary hearing that Rodriguez had given her the key). On these facts the State has not established that, with respect to the South California apartment, Fischer had “joint access or control for most purposes.” To the contrary, the Appellate Court’s determination of no common authority over the apartment was obviously correct.
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  A
  The State contends that, even if Fischer did not in fact have authority to give consent, it suffices to validate the entry that the law enforcement officers reasonably believed she did. Before reaching the merits of that contention, we must consider a jurisdictional objection: that the decision below rests on an adequate and independent state ground. Respondent asserts that the Illinois Constitution provides greater protection than is afforded under the Fourth Amendment, and that the Appellate Court relied upon this when it determined that a reasonable belief by the police officers was insufficient.
  When a state-court decision is clearly based on state law that is both adequate and independent, we will not review the decision. Michigan v. Long, 463 U. S. 1032, 1041 (1983). But when “a state court decision fairly appears to rest primarily on federal law, or to be interwoven with the federal law,” we require that it contain a “‘plain statement’ that [it] rests upon adequate and independent state grounds,” id., at 1040, 1042; otherwise, “we will accept as the most reasonable explanation that the state court decided the case the way it did because it believed that federal law required it to do so.” Id., at 1041. Here, the Appellate Court’s opinion contains no “plain statement” that its decision rests on state law. The opinion does not rely on (or even mention) any specific provision of the Illinois Constitution, nor even the Illinois Constitution generally. Even the Illinois cases cited by the opinion rely upon no constitutional provisions other than the Fourth and Fourteenth Amendments of the United States Constitution. We conclude that the Appellate Court of Illinois rested its decision on federal law.
  B
  On the merits of the issue, respondent asserts that permitting a reasonable belief of common authority to validate an entry would cause a defendant’s Fourth Amendment rights to be “vicariously waived.” Brief for Respondent 32. We disagree.
  We have been unyielding in our insistence that a defendant’s waiver of his trial rights cannot be given effect unless it is “knowing” and “intelligent.” Colorado v. Spring, 479 U. S. 564, 574-575 (1987); Johnson v. Zerbst, 304 U. S. 458 (1938). We would assuredly not permit, therefore, evidence seized in violation of the Fourth Amendment to be introduced on the basis of a trial court’s mere “reasonable belief” — derived from statements by unauthorized persons — that the defendant has waived his objection. But one must make a distinction between, on the one hand, trial rights that derive from the violation of constitutional guarantees and, on the other hand, the nature of those constitutional guarantees themselves. As we said in Schneckloth:
  “There is a vast difference between those rights that protect a fair criminal trial and the rights guaranteed under the Fourth Amendment. Nothing, either in the purposes behind requiring a ‘knowing’ and ‘intelligent’ waiver of trial rights, or in the practical application of such a requirement suggests that it ought to be extended to the constitutional guarantee against unreasonable searches and seizures.” 412 U. S., at 241.
  What Rodriguez is assured by the trial right of the exclusionary rule, where it applies, is that no evidence seized in violation of the Fourth Amendment will be introduced at his trial unless he consents. What he is assured by the Fourth Amendment itself, however, is not that no government search of his house will occur unless he consents; but that no such search will occur that is “unreasonable." U. S. Const., Arndt. 4. There are various elements, of course, that can make a search of a person’s house “reasonable” — one of which is the consent of the person or his cotenant.. The essence of respondent’s argument is that we should impose upon this element a requirement that we have not imposed upon other elements that regularly compel government officers to exercise judgment regarding the facts: namely, the requirement that their judgment be not only responsible but correct.
  The fundamental objective that alone validates all un-consented government searches is, of course, the seizure of persons who have committed or are about to commit crimes, or of evidence related to crimes. But “reasonableness,” with respect to this necessary element, does not demand that the government be factually correct in its assessment that that is what a search will produce. Warrants need only be supported by “probable cause,” which demands no more than a proper “assessment of probabilities in particular factual contexts . . . .” Illinois v. Gates, 462 U. S. 213, 232 (1983). If a magistrate, based upon seemingly reliable but factually inaccurate information, issues a warrant for the search of a house in which the sought-after felon is not present, has never been present, and was never likely to have been present, the owner of that house suffers one of the inconveniences we all expose ourselves to as the cost of living in a safe society; he does not suffer a violation of the Fourth Amendment.
  Another element often, though not invariably, required in order to render an unconsented search “reasonable” is, of course, that the officer be authorized by a valid warrant. Here also we have not held that “reasonableness” precludes error with respect to those factual judgments that law enforcement officials are expected to make. In Maryland v. Garrison, 480 U. S. 79 (1987), a warrant supported by probable cause with respect to one apartment was erroneously issued for an entire floor that was divided (though not clearly) into two apartments. We upheld the search of the apartment not properly covered by the warrant. We said:
  “[T]he validity of the search of respondent’s apartment pursuant to a warrant authorizing the search of the entire third floor depends on whether the officers’ failure to realize the overbreadth of the warrant was objectively understandable and reasonable. Here it unquestionably was. The objective facts available to the officers at the time suggested no distinction between [the suspect’s] apartment and the third-floor premises.” Id., at 88.
  The ordinary requirement of a warrant is sometimes supplanted by other elements that render the unconsented search “reasonable.” Here also we have not held that the Fourth Amendment requires factual accuracy. A warrant is not needed, for example, where the search is incident to an arrest. In Hill v. California, 401 U. S. 797 (1971), we upheld a search incident to an arrest, even though the arrest was made of the wrong person. We said:
  “The upshot was that the officers in good faith believed Miller was Hill and arrested him. They were quite wrong as it turned out, and subjective good-faith belief would not in itself justify either the arrest or the subsequent search. But sufficient probability, not certainty, is the touchstone of reasonableness under the Fourth Amendment and on the record before us the officers’ mistake was understandable and the arrest a reasonable response to the situation facing them at the time.” Id., at 803-804.
  It would be superfluous to multiply these examples. It is apparent that in order to satisfy the “reasonableness” requirement of the Fourth Amendment, what is generally demanded of the many factual determinations that must regularly be made by agents of the government — whether the magistrate issuing a warrant, the police officer executing a warrant, or the police officer conducting a search or seizure under one of the exceptions to the warrant requirement — is not that they always be correct, but that they always be reasonable. As we put it in Brinegar v. United States, 338 U. S. 160, 176 (1949):
  “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.”
  We see no reason to depart from this general rule with respect to facts bearing upon the authority to consent to a search. Whether the basis for such authority exists is the sort of recurring factual question to which law enforcement officials must be expected to apply their judgment; and all the Fourth Amendment requires is that they answer it reasonably. The Constitution is no more violated when officers enter without a warrant because they reasonably (though erroneously) believe that the person who has consented to their entry is a resident of the premises, than it is violated when they enter without a warrant because they reasonably (though erroneously) believe they are in pursuit of a violent felon who is about to escape. See Archibald v. Mosel, 677 F. 2d 5 (CA1 1982).
  Stoner v. California, 376 U. S. 483 (1964), is in our view not to the contrary. There, in holding that police had improperly entered the defendant’s hotel room based on the consent of a hotel clerk, we stated that “the rights protected by the Fourth Amendment are not to be eroded ... by unrealistic doctrines of ‘apparent authority.’” Id., at 488. It is ambiguous, of course, whether the word “unrealistic” is descriptive or limiting — that is, whether we were condemning as unrealistic all reliance upon apparent authority, or whether we were condemning only such reliance upon apparent authority as is unrealistic. Similarly ambiguous is the opinion’s earlier statement that “there [is no] substance to the claim that the search was reasonable because the police, relying upon the night clerk’s expressions of consent, had a reasonable basis for the belief that the clerk had authority to consent to the search.” Ibid. Was there no substance to it because it failed as a matter of law, or because the facts could not possibly support it? At one point the opinion does seem to speak clearly:
  “It is important to bear in mind that it was the petitioner’s constitutional right which was at stake here, and not the night clerk’s nor the hotel’s. It was a right, therefore, which only the petitioner could waive by word or deed, either directly or through an agent.” Id., at 489.
  But as we have discussed, what is at issue when a claim of apparent consent is raised is not whether the right to be free of searches has been waived, but whether the right to be free of unreasonable searches has been violated. Even if one does not think the Stoner opinion had this subtlety in mind, the supposed clarity of its foregoing statement is immediately compromised, as follows:
  “It is true that the night clerk clearly and unambiguously consented to the search. But there is nothing in the record to indicate that the police had any basis whatsoever to believe that the night clerk had been authorized by the petitioner to permit the police to search the petitioner’s room.” Ibid, (emphasis added).
  The italicized language should have been deleted, of course, if the statement two sentences earlier meant that an appearance of authority could never validate a search. In the last analysis, one must admit that the rationale of Stoner was ambiguous — and perhaps deliberately so. It is at least a reasonable reading of the case, and perhaps a preferable one, that the police could not rely upon the obtained consent because they knew it came from a hotel clerk, knew that the room was rented and exclusively occupied by the defendant, and could not reasonably have believed that the former had general access to or control over the latter. Similarly ambiguous in its implications (the Court’s opinion does not even allude to, much less discuss the effects of, “reasonable belief”) is Chapman v. United States, 365 U. S. 610 (1961). In sum, we were correct in Matlock, 415 U. S., at 177, n. 14, when we regarded the present issue as unresolved.
  As Stoner demonstrates, what we hold today does not suggest that law enforcement officers may always accept a person’s invitation to enter premises. Even when the invitation is accompanied by an explicit assertion that the person lives there, the surrounding circumstances could conceivably be such that a reasonable person would doubt its truth and not act upon it without further inquiry. As with other factual determinations bearing upon search and seizure, determination of consent to enter must “be judged against an objective standard: would the facts available to the officer at the moment . . . ‘warrant a man of reasonable caution in the belief’ ” that the consenting party had authority over the premises? Terry v. Ohio, 392 U. S. 1, 21-22 (1968). If not, then war-rantless entry without further inquiry is unlawful unless authority actually exists. But if so, the search is valid.
  * * *
  In the present case, the Appellate Court found it unnecessary to determine whether the officers reasonably believed that Fischer had the authority to consent, because it ruled as a matter of law that a reasonable belief could not validate the entry. Since we find that ruling to be in error, we remand for consideration of that question. The judgment of the Illinois Appellate Court is reversed, and the case is remanded for further proceedings not inconsistent with this opinion.
  So ordered.
  Justice MARSHALL’S dissent rests upon a rejection of the proposition that searches pursuant to valid third-party consent are “generally reasonable.” Post, at 196. Only a warrant or exigent circumstances, he contends, can produce “reasonableness”; consent validates the search only because the object of the search thereby “limit[s] his expectation of privacy,” post, at 198, so that the search becomes not really a search at all. We see no basis for making such an artificial distinction. To describe a consented search as a noninvasion of privacy and thus a nonsearch is strange in the extreme. And while it must be admitted that this ingenious device can explain why consented searches are lawful, it cannot explain why seemingly consented searches are “unreasonable,” which is all that the Constitution forbids. See Delaware v. Prouse, 440 U. S. 648, 663-654 (1979) (“The essential purpose of the proscriptions in the Fourth Amendment is to impose a standard of ‘reasonableness’ upon the exercise of discretion by government officials”). The only basis for contending that the constitutional standard could not possibly have been met here is the argument that reasonableness must be judged by the facts as they were, rather than by the facts as they were known. As we have discussed in text, that argument has long since been rejected.