opinion: MICHIGAN v. LONG
  No. 82-256.
  Argued February 23, 1983 —
  Decided July 6, 1983
  Louis J. Caruso, Solicitor General of Michigan, argued the cause for petitioner. With him on the brief were Frank J. Kelley, Attorney General, and Leonard J. Malinowski, Assistant Attorney General.
  David A. Strauss argued the cause for the United States as amicus curiae urging reversal. With him on the brief were Solicitor General Lee, Assistant Attorney General Jensen, and Deputy Solicitor General Frey.
  James H. Geary argued the cause for respondent. With him on the brief was Joseph J. Jerkins.
  David Crump, Wayne W. Schmidt, and James P. Manak filed a brief for the Gulf & Great Plains Legal Foundation of America et al. as amici curiae urging reversal.
  Justice O’Connor
  delivered the opinion of the Court.
  In Terry v. Ohio, 392 U. S. 1 (1968), we upheld the validity of a protective search for weapons in the absence of probable cause to arrest because it is unreasonable to deny a police officer the right “to neutralize the threat of physical harm,” id., at 24, when he possesses an articulable suspicion that an individual is armed and dangerous. We did not, however, expressly address whether such a protective search for weapons could extend to an area beyond the person in the absence of probable cause to arrest. In the present case, respondent David Long was convicted for possession of marihuana found by police in the passenger compartment and trunk of the automobile that he was driving. The police searched the passenger compartment because they had reason to believe that the vehicle contained weapons potentially dangerous to the officers. We hold that the protective search of the passenger compartment was reasonable under the principles articulated in Terry and other decisions of this Court. We also examine Long’s argument that the decision below rests upon an adequate and independent state ground, and we decide in favor of our jurisdiction.
  H
  Deputies Howell and Lewis were on patrol in a rural area one evening when, shortly after midnight, they observed a car traveling erratically and at excessive speed. The officers observed the car turning down a side road, where it swerved off into a shallow ditch. The officers stopped to investigate. Long, the only occupant of the automobile, met the deputies at the rear of the car, which was protruding from the ditch onto the road. The door on the driver’s side of the vehicle was left open.
  Deputy Howell requested Long to produce his operator’s license, but he did not respond. After the request was repeated, Long produced his license. Long again failed to respond when Howell requested him to produce the vehicle registration. After another repeated request, Long, who Howell thought “appeared to be under the influence of something,” 413 Mich. 461, 469, 320 N. W. 2d 866, 868 (1982), turned from the officers and began walking toward the open door of the vehicle. The officers followed Long and both observed a large hunting knife on the floorboard of the driver’s side of the car. The officers then stopped Long’s progress and subjected him to a Terry protective patdown, which revealed no weapons.
  Long and Deputy Lewis then stood by the rear of the vehicle while Deputy Howell shined his flashlight into the interior of the vehicle, but did not actually enter it. The purpose of Howell’s action was “to search for other weapons.” 413 Mich., at 469, 320 N. W. 2d, at 868. The officer noticed that something was protruding from under the armrest on the front seat. He knelt in the vehicle and lifted the armrest. He saw an open pouch on the front seat, and upon flashing his light on the pouch, determined that it contained what appeared to be marihuana. After Deputy Howell showed the pouch and its contents to Deputy Lewis, Long was arrested for possession of marihuana. A further search of the interior of the vehicle, including the glovebox, revealed neither more contraband nor the vehicle registration. The officers decided to impound the vehicle. Deputy Howell opened the trunk, which did not have a lock, and discovered inside it approximately 75 pounds of marihuana.
  The Barry County Circuit Court denied Long’s motion to suppress the marihuana taken from both the interior of the car and its trunk. He was subsequently convicted of possession of marihuana. The Michigan Court of Appeals affirmed Long’s conviction, holding that the search of the passenger compartment was valid as a protective search under Terry, swpra, and that the search of the trunk was valid as an inventory search under South Dakota v. Opperman, 428 U. S. 364 (1976). See 94 Mich. App. 338, 288 N. W. 2d 629 (1979). The Michigan Supreme Court reversed. The court held that “the sole justification of the Terry search, protection of the police officers and others nearby, cannot justify the search in this case.” 413 Mich., at 472, 320 N. W. 2d, at 869. The marihuana found in Long’s trunk was considered by the court below to be the “fruit” of the illegal search of the interior, and was also suppressed.
  We granted certiorari in this case to consider the important question of the authority of a police officer to protect himself by conducting a Terry-type search of the passenger compartment of a motor vehicle during the lawful investigatory stop of the occupant of the vehicle. 459 U. S. 904 (1982).
  II
  Before reaching the merits, we must consider Long’s argument that we are without jurisdiction to decide this case because the decision below rests on an adequate and independent state ground. The court below referred twice to the State Constitution in its opinion, but otherwise relied exclusively on federal law. Long argues that the Michigan courts have provided greater protection from searches and seizures under the State Constitution than is afforded under the Fourth Amendment, and the references to the State Constitution therefore establish an adequate and independent ground for the decision below.
  It is, of course, “incumbent upon this Court... to ascertain for itself . . . whether the asserted non-federal ground independently and adequately supports the judgment. ” Abie State Bank v. Bryan, 282 U. S. 765, 773 (1931). Although we have announced a number of principles in order to help us determine whether various forms of references to state law constitute adequate and independent state grounds, we openly admit that we have thus far not developed a satisfying and consistent approach for resolving this vexing issue. In some instances, we have taken the strict view that if the ground of decision was at all unclear, we would dismiss the case. See, e. g., Lynch v. New York ex rel. Pierson, 293 U. S. 52 (1934). In other instances, we have vacated, see, e. g., Minnesota v. National Tea Co, 309 U. S. 551 (1940), or continued a case, see, e. g., Herb v. Pitcairn, 324 U. S. 117 (1945), in order to obtain clarification about the nature of a state court decision. See also California v. Krivda, 409 U. S. 33 (1972). In more recent cases, we have ourselves examined state law to determine whether state courts have used federal law to guide their application of state law or to provide the actual basis for the decision that was reached. See Texas v. Brown, 460 U. S. 730, 732-733, n. 1 (1983) (plurality opinion). Cf. South Dakota v. Neville, 459 U. S. 553, 569 (1983) (Stevens, J., dissenting). In Oregon v. Kennedy, 456 U. S. 667, 670-671 (1982), we rejected an invitation to remand to the state court for clarification even when the decision rested in part on a case from the state court, because we determined that the state case itself rested upon federal grounds. We added that “[e]ven if the case admitted of more doubt as to whether federal and state grounds for decision were intermixed, the fact that the state court relied to the extent it did on federal grounds requires us to reach the merits.” Id., at 671.
  This ad hoc method of dealing with cases that involve possible adequate and independent state grounds is antithetical to the doctrinal consistency that is required when sensitive issues of federal-state relations are involved. Moreover, none of the various methods of disposition that we have employed thus far recommends itself as the preferred method that we should apply to the exclusion of others, and we therefore determine that it is appropriate to reexamine our treatment of this jurisdictional issue in order to achieve the consistency that is necessary.
  The process of examining state law is unsatisfactory because it requires us to interpret state laws with which we are generally unfamiliar, and which often, as in this case, have not been discussed at length by the parties. Vacation and continuance for clarification have also been unsatisfactory both because of the delay and decrease in efficiency of judicial administration, see Dixon v. Duffy, 344 U. S. 143 (1952), and, more important, because these methods of disposition place significant burdens on state courts to demonstrate the presence or absence of our jurisdiction. See Philadelphia Newspapers, Inc. v. Jerome, 434 U. S. 241, 244 (1978) (Rehnquist, J., dissenting); Department of Motor Vehicles v. Rios, 410 U. S. 425, 427 (1973) (Douglas, J., dissenting). Finally, outright dismissal of cases is clearly not a panacea because it cannot be doubted that there is an important need for uniformity in federal law, and that this need goes unsatisfied when we fail to review an opinion that rests primarily upon federal grounds and where the independence of an alleged state ground is not apparent from the four corners of the opinion. We have long recognized that dismissal is inappropriate “where there is strong indication . . . that the federal constitution as judicially construed controlled the decision below.” National Tea Co., supra, at 556.
  Respect for the independence of state courts, as well as avoidance of rendering advisory opinions, have been the cornerstones of this Court’s refusal to decide cases where there is an adequate and independent state ground. It is precisely because of this respect for state courts, and this desire to avoid advisory opinions, that we do not wish to continue to decide issues of state law that go beyond the opinion that we review, or to require state courts to reconsider cases to clarify the grounds of their decisions. Accordingly, when, as in this case, a state court decision fairly appears to rest primarily on federal law, or to be interwoven with the federal law, and when the adequacy and independence of any possible state law ground is not clear from the face of the opinion, 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. If a state court chooses merely to rely on federal precedents as it would on the precedents of all other jurisdictions, then it need only make clear by a plain statement in its judgment or opinion that the federal cases are being used only for the purpose of guidance, and do not themselves compel the result that the court has reached. In this way, both justice and judicial administration will be greatly improved. If the state court decision indicates clearly and expressly that it is alternatively based on bona fide separate, adequate, and independent grounds, we, of course, will not undertake to review the decision.
  This approach obviates in most instances the need to examine state law in order to decide the nature of the state court decision, and will at the same time avoid the danger of our rendering advisory opinions. It also avoids the unsatisfactory and intrusive practice of requiring state courts to clarify their decisions to the satisfaction of this Court. We believe that such an approach will provide state judges with a clearer opportunity to develop state jurisprudence unimpeded by federal interference, and yet will preserve the integrity of federal law. “It is fundamental that state courts be left free and unfettered by us in interpreting their state constitutions. But it is equally important that ambiguous or obscure adjudications by state courts do not stand as barriers to a determination by this Court of the validity under the federal constitution of state action.” National Tea Co., supra, at 557.
  The principle that we will not review judgments of state courts that rest on adequate and independent state grounds is based, in part, on “the limitations of our own jurisdiction.” Herb v. Pitcairn, 324 U. S. 117, 125 (1945). The jurisdictional concern is that we not “render an advisory opinion, and if the same judgment would be rendered by the state court after we corrected its views of federal laws, our review could amount to nothing more than an advisory opinion.” Id., at 126. Our requirement of a “plain statement” that a decision rests upon adequate and independent state grounds does not in any way authorize the rendering of advisory opinions. Rather, in determining, as we must, whether we have jurisdiction to review a case that is alleged to rest on adequate and independent state grounds, see Abie State Bank v. Bryan, 282 U. S., at 773, we merely assume that there are no such grounds when it is not clear from the opinion itself that the state court relied upon an adequate and independent state ground and when it fairly appears that the state court rested its decision primarily on federal law.
  Our review of the decision below under this framework leaves us unconvinced that it rests upon an independent state ground. Apart from its two citations to the State Constitution, the court below relied exclusively on its understanding of Terry and other federal cases. Not a single state case was cited to support the state court’s holding that the search of the passenger compartment was unconstitutional. Indeed, the court declared that the search in this case was unconstitutional because “[t]he Court of Appeals erroneously applied the principles of Terry v. Ohio ... to the search of the interior of the vehicle in this case.” 413 Mich., at 471, 320 N. W. 2d, at 869. The references to the State Constitution in no way indicate that the decision below rested on grounds in any way independent from the state court’s interpretation of federal law. Even if we accept that the Michigan Constitution has been interpreted to provide independent protection for certain rights also secured under the Fourth Amendment, it fairly appears in this case that the Michigan Supreme Court rested its decision primarily on federal law.
  Rather than dismissing the case, or requiring that the state court reconsider its decision on our behalf solely because of a mere possibility that an adequate and independent ground supports the judgment, we find that we have jurisdiction in the absence of a plain statement that the decision below rested on an adequate and independent state ground. It appears to us that the state court “felt compelled by what it understood to be federal constitutional considerations to construe ... its own law in the manner it did.” Zacchini v. Scripps-Howard Broadcasting Co., 433 U. S. 562, 568 (1977).
  HH J — I HH
  The court below held, and respondent Long contends, that Deputy Howell’s entry into the vehicle cannot be justified under the principles set forth in Terry because “Terry authorized only a limited pat-down search of a person suspected of criminal activity” rather than a search of an area. 413 Mich., at 472, 320 N. W. 2d, at 869 (footnote omitted). Brief for Respondent 10. Although Terry did involve the protective frisk of a person, we believe that the police action in this case is justified by the principles that we have already established in Terry and other cases.
  In Terry, the Court examined the validity of a “stop and frisk” in the absence of probable cause and a warrant. The police officer in Terry detained several suspects to ascertain their identities after the officer had observed the suspects for a brief period of time and formed the conclusion that they were about to engage in criminal activity. Because the officer feared that the suspects were armed, he patted down the outside of the suspects’ clothing and discovered two revolvers.
  Examining the reasonableness of the officer’s conduct in Terry, we held that there is “‘no ready test for determining reasonableness other than by balancing the need to search [or seize] against the invasion which the search [or seizure] entails.’” 392 U. S., at 21 (quoting Camara v. Municipal Court, 387 U. S. 523, 536-537 (1967)). Although the conduct of the officer in Terry involved a “severe, though brief, intrusion upon cherished personal security,” 392 U. S., at 24-25, we found that the conduct was reasonable when we weighed the interest of the individual against the legitimate interest in “crime prevention and detection,” id., at 22, and the “need for law enforcement officers to protect themselves and other prospective victims of violence in situations where they may lack probable cause for an arrest.” Id., at 24. When the officer has a reasonable belief “that the individual whose suspicious behavior he is investigating at close range is armed and presently dangerous to the officer or to others, it would appear to be clearly unreasonable to deny the officer the power to take necessary measures to determine whether the person is in fact carrying a weapon and to neutralize the threat of physical harm.” Ibid.
  Although Terry itself involved the stop and subsequent patdown search of a person, we were careful to note that “[w]e need not develop at length in this case, however, the limitations which the Fourth Amendment places upon a protective search and seizure for weapons. These limitations will have to be developed in the concrete factual circumstances of individual cases. ” Id., at 29. Contrary to Long’s view, Terry need not be read as restricting the preventative search to the person of the detained suspect.
  In two cases in which we applied Terry to specific factual situations, we recognized that investigative detentions involving suspects in vehicles are especially fraught with danger to police officers. In Pennsylvania v. Mimms, 434 U. S. 106 (1977), we held that police may order persons out of an automobile during a stop for a traffic violation, and may frisk those persons for weapons if there is a reasonable belief that they are armed and dangerous. Our decision rested in part on the “inordinate risk confronting an officer as he approaches a person seated in an automobile.” Id., at 110. In Adams v. Williams, 407 U. S. 143 (1972), we held that the police, acting on an informant’s tip, may reach into the passenger compartment of an automobile to remove a gun from a driver’s waistband even where the gun was not apparent to police from outside the car and the police knew of its existence only because of the tip. Again, our decision rested in part on our view of the danger presented to police officers in “traffic stop” and automobile situations.
  “The opinion in Terry authorized the frisking of an overcoat worn by defendant because that was the issue presented by the facts. One could reasonably conclude that a different result would not have been constitutionally required if the overcoat had been carried, folded over the forearm, rather than worn. The constitutional principles stated in Terry would still control.” 413 Mich., at 475-476, 320 N. W. 2d, at 871 (footnote omitted).
  Finally, we have also expressly recognized that suspects may injure police officers and others by virtue of their access to weapons, even though they may not themselves be armed. In the Term following Terry, we decided Chimel v. California, 395 U. S. 752 (1969), which involved the limitations imposed on police authority to conduct a search incident to a valid arrest. Relying explicitly on Terry, we held that when an arrest is made, it is reasonable for the arresting officer to search “the arrestee’s person and the area ‘within his immediate control’ — construing that phrase to mean the area from within which he might gain possession of a weapon or destructible evidence.” 395 U. S., at 763. We reasoned that “[a] gun on a table or in a drawer in front of one who is arrested can be as dangerous to the arresting officer as one concealed in the clothing of the person arrested.” Ibid. In New York v. Belton, 453 U. S. 454 (1981), we determined that the lower courts “have found no workable definition of ‘the area within the immediate control of the arrestee’ when that area arguably includes the interior of an automobile and the arrestee is its recent occupant.” Id., at 460. In order to provide a “workable rule,” ibid., we held that “articles inside the relatively narrow compass of the passenger compartment of an automobile are in fact generally, even if not inevitably, within ‘the area into which an arrestee might reach in order to grab a weapon’ . . . .” Ibid, (quoting Chimel, swpra, at 763). We also held that the police may examine the contents of any open or closed container found within the passenger compartment, “for if the passenger compartment is within the reach of the arrestee, so will containers in it be within his reach.” 453 U. S., at 460 (footnote omitted). See also Michigan v. Summers, 452 U. S. 692, 702 (1981).
  Our past cases indicate then that protection of police and others can justify protective searches when police have a reasonable belief that the suspect poses a danger, that roadside encounters between police and suspects are especially hazardous, and that danger may arise from the possible presence of weapons in the area surrounding a suspect. These principles compel our conclusion that the search of the passenger compartment of an automobile, limited to those areas in which a weapon may be placed or hidden, is permissible if the police officer possesses a reasonable belief based on “specific and articulable facts which, taken together with the rational inferences from those facts, reasonably warrant” the officer in believing that the suspect is dangerous and the suspect may gain immediate control of weapons. See Terry, 392 U. S., at 21. “[T]he issue is whether a reasonably prudent man in the circumstances would be warranted in the belief that his safety or that of others was in danger.” Id., at 27. If a suspect is “dangerous,” he is no less dangerous simply because he is not arrested. If, while conducting a legitimate Terry search of the interior of the automobile, the officer should, as here, discover contraband other than weapons, he clearly cannot be required to ignore the contraband, and the Fourth Amendment does not require its suppression in such circumstances. Coolidge v. New Hampshire, 403 U. S. 443, 465 (1971); Michigan v. Tyler, 436 U. S. 499, 509 (1978); Texas v. Brown, 460 U. S., at 739 (plurality opinion by Rehnquist, J.); id., at 746 (Powell, J., concurring in judgment).
  The circumstances of this case clearly justified Deputies Howell and Lewis in their reasonable belief that Long posed a danger if he were permitted to reenter his vehicle. The hour was late and the area rural. Long was driving his automobile at excessive speed, and his car swerved into a ditch. The officers had to repeat their questions to Long, who appeared to be “under the influence” of some intoxicant. Long was not frisked until the officers observed that there was a large knife in the interior of the car into which Long was about to reenter. The subsequent search of the car was restricted to those areas to which Long would generally have immediate control, and that could contain a weapon. The trial court determined that the leather pouch containing marihuana could have contained a weapon. App. 64a. It is clear that the intrusion was “strictly circumscribed by the exigencies which justified] its initiation.” Terry, supra, at 26.
  In evaulating the validity of an officer’s investigative or protective conduct under Terry, the “[tjouchstone of our analysis ... is always ‘the reasonableness in all the circumstances of the particular governmental invasion of a citizen’s personal security.’” Pennsylvania v. Mimms, 434 U. S., at 108-109 (quoting Terry, supra, at 19). In this case, the officers did not act unreasonably in taking preventive measures to ensure that there were no other weapons within Long’s immediate grasp before permitting him to reenter his automobile. Therefore, the balancing required by Terry clearly weighs in favor of allowing the police to conduct an area search of the passenger compartment to uncover weapons, as long as they possess an articulable and objectively reasonable belief that the suspect is potentially dangerous.
  The Michigan Supreme Court appeared to believe that it was not reasonable for the officers to fear that Long could injure them, because he was effectively under their control during the investigative stop and could not get access to any weapons that might have been located in the automobile. See 413 Mich., at 472, 320 N. W. 2d, at 869. This reasoning is mistaken in several respects. During any investigative detention, the suspect is “in the control” of the officers in the sense that he “may be briefly detained against his will. . . .” Terry, supra, at 34 (White, J., concurring). Just as a Terry suspect on the street may, despite being under the brief control of a police officer, reach into his clothing and retrieve a weapon, so might a Terry suspect in Long’s position break away from police control and retrieve a weapon from his automobile. See United States v. Rainone, 586 F. 2d 1132, 1134 (CA71978), cert. denied, 440 U. S. 980 (1979). In addi-
  tion, if the suspect is not placed under arrest, he will be permitted to reenter his automobile, and he will then have access to any weapons inside. United States v. Powless, 546 F. 2d 792, 795-796 (CA8), cert. denied, 430 U. S. 910 (1977). Or, as here, the suspect may be permitted to reenter the vehicle before the Terry investigation is over, and again, may have access to weapons. In any event, we stress that a Terry investigation, such as the one that occurred here, involves a police investigation “at close range,” Terry, 392 U. S., at 24, when the officer remains particularly vulnerable in part because a full custodial arrest has not been effected, and the officer must make a “quick decision as to how to protect himself and others from possible danger . . . .” Id., at 28. In such circumstances, we have not required that officers adopt alternative means to ensure their safety in order to avoid the intrusion involved in a Terry encounter.
  HH <
  The trial court and the Court of Appeals upheld the search of the trunk as a valid inventory search under this Court’s decision in South Dakota v. Opperman, 428 U. S. 364 (1976). The Michigan Supreme Court did not address this holding, and instead suppressed the marihuana taken from the trunk as a fruit of the illegal search of the interior of the automobile. Our holding that the initial search was justified under Terry makes it necessary to determine whether the trunk search was permissible under the Fourth Amendment. However, we decline to address this question because it was not passed upon by the Michigan Supreme Court, whose decision we review in this case. See Cardinale v. Louisiana, 394 U. S. 437, 438 (1969). We remand this issue to the court below, to enable it to determine whether the trunk search was permissible under Opperman, supra, or other decisions of this Court. See, e. g., United States v. Ross, 456 U. S. 798 (1982).
  V
  The judgment of the Michigan Supreme Court is reversed, and the case is remanded for further proceedings not inconsistent with this opinion.
  It is so ordered.
  It is clear, and the respondent concedes, that if the officers had arrested Long for speeding or for driving while intoxicated, they could have searched the passenger compartment under New York v. Belton, 453 U. S. 454 (1981), and the trunk under United States v. Ross, 456 U. S. 798 (1982), if they had probable cause to believe that the trunk contained contraband. See Tr. of Oral Arg. 41. However, at oral argument, the State informed us that while Long could have been arrested for a speeding violation under Michigan law, he was not arrested because “[a]s a matter of practice,” police in Michigan do not arrest for speeding violations unless “more” is involved. See id., at 6. The officers did issue Long an appearance ticket. The petitioner also confirmed that the officers could have arrested Long for driving while intoxicated but they “would have to go through a process to make a determination as to whether the party is intoxicated and then go from that point.” Ibid.
  The court below treated this case as involving a protective search, and not a search justified by probable cause to arrest for speeding, driving while intoxicated, or any other offense. Further, the petitioner does not argue that if probable cause to arrest exists, but the officers do not actually effect the arrest, the police may nevertheless conduct a search as broad as those authorized by Belton and Ross. Accordingly, we do not address that issue.
  Chief Justice Coleman dissented, arguing that Terry v. Ohio, 392 U. S. 1 (1968), authorized the area search, and that the trunk search was a valid inventory search. See 413 Mich., at 473-480, 320 N. W. 2d, at 870-873. Justice Moody concurred in the result on the ground that the trunk search was improper. He agreed with Chief Justice Coleman that the interior search was proper under Terry. See 413 Mich., at 480-486, 320 N. W. 2d, at 873-875.
  On the first occasion, the court merely cited in a footnote both the State and Federal Constitutions. See id., at 471, n. 4, 320 N. W. 2d, at 869, n. 4. On the second occasion, at the conclusion of the opinion, the court stated: “We hold, therefore, that the deputies’ search of the vehicle was proscribed by the Fourth Amendment to the United States Constitution and art. 1, §11 of the Michigan Constitution.” Id., at 472-473, 320 N. W. 2d, at 870.
  For example, we have long recognized that “where the judgment of a state court rests upon two grounds, one of which is federal and the other non-federal in character, our jurisdiction fails if the non-federal ground is independent of the federal ground and adequate to support the judgment.” Fox Film Corp. v. Muller, 296 U. S. 207, 210 (1935). We may review a state case decided on a federal ground even if it is clear that there was an available state ground for decision on which the state court could properly have relied. Beecher v. Alabama, 389 U. S. 35, 37, n. 3 (1967). Also, if, in our view, the state court “ ‘felt compelled by what it understood to be federal constitutional considerations to construe ... its own law in the manner it did,’ ” then we will not treat a normally adequate state ground as independent, and there will be no question about our jurisdiction. Delaware v. Prouse, 440 U. S. 648, 653 (1979) (quoting Zacchini v. Scripps-Howard Broadcasting Co., 433 U. S. 562, 568 (1977)). See also South Dakota v. Neville, 459 U. S. 553, 556-557, n. 3 (1983). Finally, “where the non-federal ground is so interwoven with the [federal ground] as not to be an independent matter, or is not of sufficient breadth to sustain the judgment without any decision of the other, our jurisdiction is plain.” Enterprise Irrigation District v. Farmers Mutual Canal Co., 243 U. S. 157, 164 (1917).
  Indeed, Dixon v. Duffy is also illustrative of another difficulty involved in our requiring state courts to reconsider their decisions for purposes of clarification. In Dixon, we continued the case on two occasions in order to obtain clarification, but none was forthcoming: “[T]he California court advised petitioner’s counsel informally that it doubted its jurisdiction to render such a determination.” 344 U, S., at 145. We then vacated the judgment of the state court, and remanded.
  There may be certain circumstances in which clarification is necessary or desirable, and we will not be foreclosed from taking the appropriate action.
  In Herb v. Pitcairn, 324 U. S., at 128, the Court also wrote that it was desirable that state courts “be asked rather than told what they have intended. ” It is clear that we have already departed from that view in those cases in which we have examined state law to determine whether a particular result was guided or compelled by federal law. Our decision today departs further from Herb insofar as we disfavor further requests to state courts for clarification, and we require a clear and express statement that a decision rests on adequate and independent state grounds. However, the “plain statement” rule protects the integrity of state courts for the reasons discussed above. The preference for clarification expressed in Herb has failed to be a completely satisfactory means of protecting the state and federal interests that are involved.
  It is not unusual for us to employ certain presumptions in deciding jurisdictional issues. For instance, although the petitioner bears the burden of establishing our jurisdiction, Durley v. Mayo, 351 U. S. 277, 285 (1956), we have held that the party who alleges that a controversy before us has become moot has the “heavy burden” of establishing that we lack jurisdiction. County of Los Angeles v. Davis, 440 U. S. 625, 631 (1979). That is, we presume in those circumstances that we have jurisdiction until some party establishes that we do not for reasons of mootness.
  We also note that the rule that we announce today was foreshadowed by our opinions in Delaware v. Prouse, 440 U. S. 648 (1979), and Zacchini v. Scripps-Howard Broadcasting Co., 433 U. S. 562 (1977). In these cases, the state courts relied on both state and federal law. We determined that we had jurisdiction to decide the cases because our reading of the opinions led us to conclude that each court “felt compelled by what it understood to be federal constitutional considerations to construe and apply its own law in the manner it did.” Zacchini, supra, at 568; Delaware, supra, at 653. In Delaware, we referred to prior state decisions that confirmed our understanding of the opinion in that case, but our primary focus was on the face of the opinion. In Zacchini, we relied entirely on the syllabus and opinion of the state court.
  In dissent, Justice Stevens proposes the novel view that this Court should never review a state court decision unless the Court wishes to vindicate a federal right that has been endangered. The rationale of the dissent is not restricted to cases where the decision is arguably supported by adequate and independent state grounds. Rather, Justice Stevens appears to believe that even if the decision below rests exclusively on federal grounds, this Court should not review the decision as long as there is no federal right that is endangered.
  The state courts handle the vast bulk of all criminal litigation in this country. In 1982, more than 12 million criminal actions (excluding juvenile and traffic charges) were filed in the 50 state court systems and the District of Columbia. See 7 State Court Journal, No. 1, p. 18 (1983). By comparison, approximately 32,700 criminal suits were filed in federal courts during that same year. See Annual Report of the Director of the Administrative Office of the United States Courts 6 (1982). The state courts are required to apply federal constitutional standards, and they necessarily create a considerable body of “federal law” in the process. It is not surprising that this Court has become more interested in the application and development of federal law by state courts in the light of the recent significant expansion of federally created standards that we have imposed on the States.
  At oral argument, Long argued that the state court relied on its decision in People v. Reed, 393 Mich. 342, 224 N. W. 2d 867, cert. denied, 422 U. S. 1044 (1975). See Tr. of Oral Arg. 29. However, the court cited that ease only in the context of a statement that the State did not seek to justify the search in this case “by reference to other exceptions to the warrant requirement.” 413 Mich., at 472, 320 N. W. 2d, at 869-870 (footnote omitted). The court then noted that Reed held that ‘“[a] warrantless search and seizure is unreasonable per se and violates the Fourth Amendment of the United States Constitution and Art. 1, § 11 of the state constitution unless shown to be within one of the exceptions to the rule.’ ” 413 Mich., at 472-473, n. 8, 320 N. W. 2d, at 870, n. 8.
  There is nothing unfair about requiring a plain statement of an independent state ground in this case. Even if we were to rest our decision on an evaluation of the state law relevant to Long’s claim, as we have sometimes done in the past, our understanding of Michigan law would also result in our finding that we have jurisdiction to decide this case. Under state search-and-seizure law, a “higher standard” is imposed under Art. 1, § 11, of the 1963 Michigan Constitution. See People v. Secrest, 413 Mich. 521, 525, 321 N. W. 2d 368, 369 (1982). If, however, the item seized is, inter alia, a “narcotic drug . . . seized by a peace officer outside the curtilage of any dwelling house in this state,” Art. 1, § 11, of the 1963 Michigan Constitution, then the seizure is governed by a standard identical to that imposed by the Fourth Amendment. See People v. Moore, 391 Mich. 426, 435, 216 N. W. 2d 770, 775 (1974).
  Long argues that under the current Michigan Comp. Laws §333.7107 (1979), the definition of a “narcotic” does not include marihuana. The difficulty with this argument is that Long fails to cite any authority for the proposition that the term “narcotic” as used in the Michigan Constitution is dependent on current statutory definitions of that term. Indeed, it appears that just the opposite is true. The Michigan Supreme Court has held that constitutional provisions are presumed “to be interpreted in accordance with existing laws and legal usages of the time” of the passage of the provision. Bacon v. Kent-Ottawa Authority, 354 Mich. 159, 169, 92 N. W. 2d 492, 497 (1958). If the state legislature were able to change the interpretation of a constitutional provision by statute, then the legislature would have “the power of outright repeal of a duly-voted constitutional provision.” Ibid. Applying these principles, the Michigan courts have held that a statute passed subsequent to the applicable state constitutional provision is not relevant for interpreting its Constitution, and that a definition in a legislative Act pertains only to that Act. Jones v. City of Ypsilanti, 26 Mich. App. 574, 182 N. W. 2d 795 (1970). See also Walber v. Piggins, 2 Mich. App. 145, 138 N. W. 2d 772 (1966), aff’d, 381 Mich. 138, 160 N. W. 2d 876 (1968). At the time that the 1963 Michigan Constitution was enacted, it is clear that marihuana was considered a narcotic drug. See 1961 Mich. Pub. Acts, No. 206, § 1(f). Indeed, it appears that marihuana was considered a narcotic drug in Michigan until 1978, when it was removed from the narcotic classification. We would conclude that the seizure of marihuana in Michigan is not subject to analysis under any “higher standard” than may be imposed on the seizure of other items. In the light of our holding in Delaware v. Prouse, 440 U. S. 648 (1979), that an interpretation of state law in our view compelled by federal constitutional considerations is not an independent state ground, we would have jurisdiction to decide the case.
  Although we did not in any way weaken the warrant requirement, we acknowledged that the typical “stop and frisk” situation involves “an entire rubric of police conduct — necessarily swift action predicated upon the on-the-spot observations of the officer on the beat — which historically has not been, and as a practical matter could not be, subjected to the warrant procedure. Instead, the conduct in this case must be tested by the Fourth Amendment’s general proscription against unreasonable searches and seizures.” Terry, 392 U. S., at 20 (footnote omitted). We have emphasized that the propriety of a Terry stop and frisk is to be judged according to whether the officer acted as a “reasonably prudent man” in deciding that the intrusion was justified. Id., at 27. “A brief stop of a suspicious individual, in order to determine his identity or to maintain the status quo momentarily while obtaining more information, may be most reasonable in light of the facts known to the officer at the time.” Adams v. Williams, 407 U. S. 143, 146 (1972).
  As Chief Justice Coleman noted in her dissenting opinion in the present case:
  According to one study, “approximately 30% of police shootings occurred when a police officer approached a suspect seated in an automobile. Bristow, Police Officer Shootings — A Tactical Evaluation, 54 J. Crim. L. C. & P. S. 93 (1963).” Adams v. Williams, supra, at 148, n. 3.
  We stress that our decision does not mean that the police may conduct automobile searches whenever they conduct an investigative stop, although the “bright line” that we drew in Belton clearly authorizes such a search whenever officers effect a custodial arrest. An additional interest exists in the arrest context, i. e., preservation of evidence, and this justifies an “automatic” search. However, that additional interest does not exist in the Terry context. A Terry search, “unlike a search without a warrant incident to a lawful arrest, is not justified by any need to prevent the disappearance or destruction of evidence of crime. . . . The sole justification of the search ... is the protection of the police officer and others nearby . . . .” 392 U. S., at 29. What we borrow now from Chimel v. California, 395 U. S. 752 (1969), and Belton is merely the recognition that part of the reason to allow area searches incident to an arrest is that the arrestee, who may not himself be armed, may be able to gain access to weapons to injure officers or others nearby, or otherwise to hinder legitimate police activity. This recognition applies as well in the Terry context. However, because the interest in collecting and preserving evidence is not present in the Terry context, we require that officers who conduct area searches during investigative detentions must do so only when they have the level of suspicion identified in Terry.
  Of course, our analysis would apply to justify the search of Long’s person that was conducted by the officers after the discovery of the knife.
  Long makes a number of arguments concerning the invalidity of the search of the passenger compartment. The thrust of these arguments is that Terry searches are limited in scope and that an area search is fundamentally inconsistent with this limited scope. We have recognized that Terry searches are limited insofar as they may not be conducted in the absence of an articulable suspicion that the intrusion is justified, see, e. g., Sibron v. New York, 392 U. S. 40, 65 (1968), and that they are protective in nature and limited to weapons, see Ybarra v. Illinois, 444 U. S. 85, 93-94 (1979). However, neither of these concerns is violated by our decision. To engage in an area search, which is limited to seeking weapons, the officer must have an articulable suspicion that the suspect is potentially dangerous.
  Long also argues that there cannot be a legitimate Terry search based on the discovery of the hunting knife because Long possessed that weapon legally. See Brief for Respondent 17. Assuming, arguendo, that Long possessed the knife lawfully, we have expressly rejected the view that the validity of a Terry search depends on whether the weapon is possessed in accordance with state law. See Adams v. Williams, 407 U. S., at 146.
  Contrary to Justice Brennan’s suggestion in dissent, the reasoning of Terry, Chimel, and Belton points clearly to the direction that we have taken today. Although Chimel involved a full custodial arrest, the rationale for Chimel rested on the recognition in Terry that it is unreasonable to prevent the police from taking reasonable steps to protect their safety.
  Justice Brennan suggests that we are expanding the scope of a Terry-type search to include a search incident to a valid arrest. However, our opinion clearly indicates that the area search that we approve is limited to a search for weapons in circumstances where the officers have a reasonable belief that the suspect is potentially dangerous to them. Justice Brennan quotes at length from Sibron, but fails to recognize that the search in that case was a search for narcotics, and not a search for weapons.
  Justice Brennan concedes that “police should not be exposed to unnecessary danger in the performance of their duties,” post, at 1064, but then would require that police officers, faced with having to make quick determinations about self-protection and the defense of innocent citizens in the area, must also decide instantaneously what “less intrusive” alternative exists to ensure that any threat presented by the suspect will be neutralized. Post, at 1065. For the practical reasons explained in Terry, 392 U. S., at 24, 28, we have never required police to adopt alternative measures to avoid a legitimate Terry-type intrusion.
  Long suggests that the trunk search is invalid under state law. See Tr. of Oral Arg. 41, 43-44. The Michigan Supreme Court is, of course, free to determine the validity of that search under state law.
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