Opinion

JUSTICE O'CONNOR delivered the opinion of the Court.

In this case, we must decide whether, in order to observe a Vehicle Identification Number (VIN) generally visible from outside an automobile, a police officer may reach into the passenger compartment of a vehicle to move papers obscuring the VIN after its driver has been stopped for a traffic violation and has exited the car. We hold that, in these circumstances, the police officer's action does not violate the Fourth Amendment.

I

On the afternoon of May 11, 1981, New York City police officers Lawrence Meyer and William McNamee observed respondent Benigno Class driving above the speed limit in a car with a cracked windshield. Both driving with a cracked windshield and speeding are traffic violations under New York law. See N.Y.Veh. & Traf.Law §§ 375(22), 1180(d) (McKinney 1970). Respondent followed the officers' ensuing directive to pull over. Respondent then emerged from his car and approached Officer Meyer. Officer McNamee went directly to respondent's vehicle. Respondent provided Officer Meyer with a registration certificate and proof of insurance, but stated that he had no driver's license.

Meanwhile, Officer McNamee opened the door of respondent's car to look for the VIN, which is located on the left doorjamb in automobiles manufactured before 1969. When the officer did not find the VIN on the doorjamb, he reached into the interior of respondent's car to move some papers obscuring the area of the dashboard where the VIN is located in later model automobiles. In doing so, Officer McNamee saw the handle of a gun protruding about one inch from underneath the driver's seat. The officer seized the gun, and respondent was promptly arrested. Respondent was also issued summonses for his traffic violations.

It is undisputed that the police officers had no reason to suspect that respondent's car was stolen, that it contained contraband, or that respondent had committed an offense other than the traffic violations. Nor is it disputed that respondent committed the traffic violations with which he was charged, and that, as of the day of the arrest, he had not been issued a valid driver's license.

After the state trial court denied a motion to suppress the gun as evidence, respondent was convicted of criminal possession of a weapon in the third degree. See N.Y. Penal Law § 265.02(4) (McKinney 1980). The Appellate Division of the New York Supreme Court upheld the conviction without opinion. 97 App.Div.2d 741, 468 N.Y.S.2d 892 (1983). The New York Court of Appeals reversed. It reasoned that the police officer's "intrusion... was undertaken to obtain information and it exposed... hidden areas" of the car, and "therefore constituted a search." 63 N.Y.2d 491, 495, 472 N.E.2d 1009, 1011 (1984). Although it recognized that a search for a VIN generally involves a minimal intrusion because of its limited potential locations, and agreed that there is a compelling law enforcement interest in positively identifying vehicles involved in accidents or automobile thefts, the court thought it decisive that the facts of this case "reveal no reason for the officer to suspect other criminal activity [besides the traffic infractions] or to act to protect his own safety." Id. at 495-496, 472 N.E.2d at 1012. The state statutory provision that authorizes officers to demand that drivers reveal their VIN "provided no justification for the officer's entry of [respondent's] car." Id. at 497, 472 N.E.2d at 1013. If the officer had taken advantage of that statute and asked to see the VIN, respondent could have moved the papers away himself, and no intrusion would have occurred. In the absence of any justification for the search besides the traffic infractions, the New York Court of Appeals ruled that the gun must be excluded from evidence.

We granted certiorari, 471 U.S. 1003 (1985), and now reverse.

II

Respondent asserts that this Court is without jurisdiction to hear this case because the decision of the New York Court of Appeals rests on an adequate and independent state ground. We disagree.

The opinion of the New York Court of Appeals mentions the New York Constitution but once, and then only in direct conjunction with the United States Constitution. 63 N.Y.2d at 493, 472 N.E.2d at 1010. Cf. Michigan v. Long, 463 U. S. 1032, 463 U. S. 1043 (1983). The opinion below makes use of both federal and New York cases in its analysis, generally citing both for the same proposition. See, e.g., 63 N.Y.2d at 494, 495, 472 N.E.2d at 1011. The opinion lacks the requisite "plain statement" that it rests on state grounds. Michigan v. Long, supra, at 463 U. S. 1042, 463 U. S. 1044. Accordingly, our holding in Michigan v. Long is directly applicable here:

[W]hen... 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.

463 U.S. at 463 U. S. 1040 -1041. See also California v. Carney, 471 U. S. 386, 471 U. S. 389, n. 1 (1985).

Respondent's claim that the opinion below rested on independent and adequate state statutory grounds is also without merit. The New York Court of Appeals did not hold that § 401 of New York's Vehicle and Traffic Law prohibited the search at issue here, but, in rejecting an assertion of petitioner, merely held that § 401 "provided no justification " for a search. 63 N.Y.2d at 497, 472 N.E.2d at 1013 (emphasis added). In determining that the police officer's action was prohibited, the court below looked to the Federal Constitution, not the State's statute. Moreover, New York adheres to the general rule that, when statutory construction can resolve a case, courts should not decide constitutional issues. See Ashwander v. TVA, 297 U. S. 288, 297 U. S. 346 -347 (1936) (Brandeis, J., concurring); In re Peters v. New York City Housing Authority, 307 N.Y. 519, 527, 121 N.E.2d 529, 531 (1954). Since the New York Court of Appeals discussed both statutory and constitutional grounds, we may infer that the court believed the statutory issue insufficient to resolve the case. The discussion of the statute therefore could not have constituted an independent and adequate state ground.

III

A

The officer here, after observing respondent commit two traffic violations and exit the car, attempted to determine the VIN of respondent's automobile. In reaching to remove papers obscuring the VIN, the officer intruded into the passenger compartment of the vehicle.

The VIN consists of more than a dozen digits, unique to each vehicle and required on all cars and trucks. See 49 CFR § 571.115 (1984). The VIN is roughly analogous to a serial number, but it can be deciphered to reveal not only the place of the automobile in the manufacturer's production run but also the make, model, engine type, and place of manufacture of the vehicle. See § 565.4.

The VIN is a significant thread in the web of regulation of the automobile. See generally 43 Fed.Reg. 2189 (1978). The ease with which the VIN allows identification of a particular vehicle assists the various levels of government in many ways. For the Federal Government, the VIN improves the efficacy of recall campaigns, and assists researchers in determining the risks of driving various makes and models of automobiles. In combination with state insurance laws, the VIN reduces the number of those injured in accidents who go uncompensated for lack of insurance. In conjunction with the State's registration requirements and safety inspections, the VIN helps to ensure that automobile operators are driving safe vehicles. By making automobile theft more difficult, the VIN safeguards not only property but also life and limb. See 33 Fed.Reg. 10207 (1968) (noting that stolen vehicles are disproportionately likely to be involved in automobile accidents).

To facilitate the VIN's usefulness for these laudable governmental purposes, federal law requires that the VIN be placed in the plain view of someone outside the automobile:

The VIN for passenger cars [manufactured after 1969] shall be located inside the passenger compartment. It shall be readable, without moving any part of the vehicle, through the vehicle glazing under daylight lighting conditions by an observer having 20/20 vision (Snellen) whose eye point is located outside the vehicle adjacent to the left windshield pillar. Each character in the VIN subject to this paragraph shall have a minimum height of 4 mm.

49 CFR § 571.115 (S4.6) (1984) (emphasis added).

In Delaware v. Prouse, 440 U. S. 648, 440 U. S. 658 (1979), we recognized the "vital interest" in highway safety and the various programs that contribute to that interest. In light of the important interests served by the VIN, the Federal and State Governments are amply justified in making it a part of the web of pervasive regulation that surrounds the automobile, and in requiring its placement in an area ordinarily in plain view from outside the passenger compartment.

B

A citizen does not surrender all the protections of the Fourth Amendment by entering an automobile. See Delaware v. Prouse, supra, at 440 U. S. 663 ; Almeida-Sanchez v. United States, 413 U. S. 266, 413 U. S. 269 (1973). Nonetheless, the State's intrusion into a particular area, whether in an automobile or elsewhere, cannot result in a Fourth Amendment violation unless the area is one in which there is a "constitutionally protected reasonable expectation of privacy." Katz v. United States, 389 U. S. 347, 389 U. S. 360 (1967) (Harlan, J., concurring). See Oliver v. United States, 466 U. S. 170, 466 U. S. 177 -180 (1984); Maryland v. Macon, 472 U. S. 463, 472 U. S. 469 (1985).

The Court has recognized that the physical characteristics of an automobile and its use result in a lessened expectation of privacy therein:

One has a lesser expectation of privacy in a motor vehicle because its function is transportation and it seldom serves as one's residence or as the repository of personal effects. A car has little capacity for escaping public scrutiny. It travels public thoroughfares where both its occupants and its contents are in plain view.

Cardwell v. Lewis, 417 U. S. 583, 417 U. S. 590 (1974) (plurality opinion). Moreover, automobiles are justifiably the subject of pervasive regulation by the State. Every operator of a motor vehicle must expect that the State, in enforcing its regulations, will intrude to some extent upon that operator's privacy.

Automobiles, unlike homes, are subject to pervasive and continuing governmental regulation and controls, including periodic inspection and licensing requirements. As an everyday occurrence, police stop and examine vehicles when license plates or inspection stickers have expired, or if other violations, such as exhaust fumes or excessive noise, are noted, or if headlights or other safety equipment are not in proper working order.

South Dakota v. Opperman, 428 U. S. 364, 428 U. S. 368 (1976). See also Cady v. Dombrowski, 413 U. S. 433, 413 U. S. 441 -442 (1973); California v. Carney, 471 U.S. at 471 U. S. 392.

The factors that generally diminish the reasonable expectation of privacy in automobiles are applicable a fortiori to the VIN. As we have discussed above, the VIN plays an important part in the pervasive regulation by the government of the automobile. A motorist must surely expect that such regulation will on occasion require the State to determine the VIN of his or her vehicle, and the individual's reasonable expectation of privacy in the VIN is thereby diminished. This is especially true in the case of a driver who has committed a traffic violation. See Delaware v. Prouse, supra, at 440 U. S. 659 ("The foremost method of enforcing traffic and vehicle safety regulations... is acting upon observed violations. Vehicle stops for traffic violations occur countless times each day; and on these occasions, licenses and registration papers are subject to inspection and drivers without them will be ascertained ") (emphasis added). In addition, it is unreasonable to have an expectation of privacy in an object required by law to be located in a place ordinarily in plain view from the exterior of the automobile. The VIN's mandated visibility makes it more similar to the exterior of the car than to the trunk or glove compartment. The exterior of a car, of course, is thrust into the public eye, and thus to examine it does not constitute a "search." See Cardwell v. Lewis, supra, at 417 U. S. 588 -589. In sum, because of the important role played by the VIN in the pervasive governmental regulation of the automobile and the efforts by the Federal Government to ensure that the VIN is placed in plain view, we hold that there was no reasonable expectation of privacy in the VIN.

We think it makes no difference that the papers in respondent's car obscured the VIN from the plain view of the officer. We have recently emphasized that efforts to restrict access to an area do not generate a reasonable expectation of privacy where none would otherwise exist. See Oliver v. United States, supra, at 466 U. S. 182 -184 (placement of "No Trespassing" signs on secluded property does not create "legitimate privacy interest" in marihuana fields). Here, where the object at issue is an identification number behind the transparent windshield of an automobile driven upon the public roads, we believe that the placement of the obscuring papers was insufficient to create a privacy interest in the VIN. The mere viewing of the formerly obscured VIN was not, therefore, a violation of the Fourth Amendment.

C

The evidence that respondent sought to have suppressed was not the VIN, however, but a gun, the handle of which the officer saw from the interior of the car while reaching for the papers that covered the VIN. While the interior of an automobile is not subject to the same expectations of privacy that exist with respect to one's home, a car's interior as a whole is nonetheless subject to Fourth Amendment protection from unreasonable intrusions by the police. We agree with the New York Court of Appeals that the intrusion into that space constituted a "search." 63 N.Y.2d at 495, 472 N.E.2d at 1011. Cf. Delaware v. Prouse, 440 U.S. at 440 U. S. 653 ("[S]topping an automobile and detaining its occupants constitute a seizure'... even though the purpose of the stop is limited and the resulting detention quite brief"). We must decide, therefore, whether this search was constitutionally permissible.

If respondent had remained in the car, the police would have been justified in asking him to move the papers obscuring the VIN. New York law authorizes a demand by officers to see the VIN, see 63 N.Y.2d at 496-497, 472 N.E.2d at 1012-1013, and even if the state law were not explicit on this point, we have no difficulty in concluding that a demand to inspect the VIN, like a demand to see license and registration papers, is within the scope of police authority pursuant to a traffic violation stop. See Prouse, supra, at 440 U. S. 659. If respondent had stayed in his vehicle and acceded to such a request from the officer, the officer would not have needed to intrude into the passenger compartment. Respondent chose, however, to exit the vehicle without removing the papers that covered the VIN; the officer chose to conduct his search without asking respondent to return to the car. We must therefore decide whether the officer acted within the bounds of the Fourth Amendment in conducting the search. We hold that he did.

Keeping the driver of a vehicle in the car during a routine traffic stop is probably the typical police practice. See D. Schultz & D. Hunt, Traffic Investigation and Enforcement 17 (1983). Nonetheless, out of a concern for the safety of the police, the Court has held that officers may, consistent with the Fourth Amendment, exercise their discretion to require a driver who commits a traffic violation to exit the vehicle even though they lack any particularized reason for believing the driver possesses a weapon. Pennsylvania v. Mimms, 434 U.S. 106, 434 U. S. 108 -111 (1977) (per curiam). While we impute to respondent no propensity for violence, and while we are conscious of the fact that respondent here voluntarily left the vehicle, the facts of this case may be used to illustrate one of the principal justifications for the discretion given police officers by Pennsylvania v. Mimms: while in the driver's seat, respondent had a loaded pistol at hand. Mimms allows an officer to guard against that possibility by requiring the driver to exit the car briefly. Clearly, Mimms also allowed the officers here to detain respondent briefly outside the car that he voluntarily exited while they completed their investigation.

The question remains, however, as to whether the officers could not only effect the seizure of respondent necessary to detain him briefly outside the vehicle, but also effect a search for the VIN that may have been necessary only because of that detention. The pistol beneath the seat did not, of course, disappear when respondent closed the car door behind him. To have returned respondent immediately to the automobile would have placed the officers in the same situation that the holding in Mimms allows officers to avoid -permitting an individual being detained to have possible access to a dangerous weapon and the benefit of the partial concealment provided by the car's exterior. See Pennsylvania v. Mimms, supra, at 434 U. S. 110. In light of the danger to the officers' safety that would have been presented by returning respondent immediately to his car, we think the search to obtain the VIN was not prohibited by the Fourth Amendment.

The Fourth Amendment, by its terms, prohibits "unreasonable" searches and seizures. We have noted:

[T]here 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. Camara v. Municipal Court, 387 U. S. 523, 387 U. S. 534 -535, 387 U. S. 536 -637 (1967). And in justifying the particular intrusion, the police officer must be able to point to specific and articulable facts which, taken together with rational inferences from those facts, justifiably warrant that intrusion.

Terry v. Ohio, 392 U. S. 1, 392 U. S. 21 (1968) (footnote omitted) (brackets as in Terry ). This test generally means that searches must be conducted pursuant to a warrant backed by probable cause. See United States v. Ventresca, 380 U. S. 102, 380 U. S. 105 -109 (1965); United States v. Karo, 468 U. S. 705, 468 U. S. 714 -715 (1984). When a search or seizure has as its immediate object a search for a weapon, however, we have struck the balance to allow the weighty interest in the safety of police officers to justify warrantless searches based only on a reasonable suspicion of criminal activity. See Terry v. Ohio, supra; Adams v. Williams, 407 U. S. 143 (1972). Such searches are permissible despite their substantial intrusiveness. See Terry v. Ohio, supra, at 392 U. S. 24 -25 (search was "a severe, though brief, intrusion upon cherished personal security, and... must surely [have] b[een] an annoying, frightening, and perhaps humiliating experience").

When the officer's safety is less directly served by the detention, something more than objectively justifiable suspicion is necessary to justify the intrusion if the balance is to tip in favor of the legality of the governmental intrusion. In Pennsylvania v. Mimms, supra, at 434 U. S. 107, the officers had personally observed the seized individual in the commission of a traffic offense before requesting that he exit his vehicle. In Michigan v. Summers, 452 U. S. 692, 452 U. S. 693 (1981), the officers had obtained a warrant to search the house that the person seized was leaving when they came upon him. While the facts in Pennsylvania v. Mimms and Michigan v. Summers differ in some respects from the facts of this case, the similarities are strong enough that the balancing of governmental interests against governmental intrusion undertaken in those cases is also appropriate here. All three of the factors involved in Mimms and Summers are present in this case: the safety of the officers was served by the governmental intrusion; the intrusion was minimal; and the search stemmed from some probable cause focusing suspicion on the individual affected by the search. Indeed, here the officers' probable cause stemmed from directly observing respondent commit a violation of the law.

When we undertake the necessary balancing of

the nature and quality of the intrusion on the individual's Fourth Amendment interests against the importance of the governmental interests alleged to justify the intrusion,

United States v. Place, 462 U. S. 696, 462 U. S. 703 (1983), the conclusion that the search here was permissible follows. As we recognized in Delaware v. Prouse, 440 U.S. at 440 U. S. 658, the governmental interest in highway safety served by obtaining the VIN is of the first order, and the particular method of obtaining the VIN here was justified by a concern for the officers' safety. The "critical" issue of the intrusiveness of the government's action, United States v. Place, supra, at 462 U. S. 722 (BLACKMUN, J., concurring in judgment), also here weighs in favor of allowing the search. The search was focused in its objective and no more intrusive than necessary to fulfill that objective. The search was far less intrusive than a formal arrest, which would have been permissible for a traffic offense under New York law, see N.Y.Veh. & Traf.Law § 155 (McKinney Supp.1986); N.Y.Crim.Proc.Law § 140.10(1) (McKinney 1981), and little more intrusive than a demand that respondent -under the eyes of the officers -move the papers himself. The VIN, which was the clear initial objective of the officer, is by law present in one of two locations -either inside the doorjamb or atop the dashboard, and thus ordinarily in plain view of someone outside the automobile. Neither of those locations is subject to a reasonable expectation of privacy. The officer here checked both those locations, and only those two locations. The officer did not root about the interior of respondent's automobile before proceeding to examine the VIN. He did not reach into any compartments or open any containers. He did not even intrude into the interior at all until after he had checked the doorjamb for the VIN. When he did intrude, the officer simply reached directly for the unprotected space where the VIN was located to move the offending papers. We hold that this search was sufficiently unintrusive to be constitutionally permissible in light of the lack of a reasonable expectation of privacy in the VIN and the fact that the officers observed respondent commit two traffic violations. Any other conclusion would expose police officers to potentially grave risks without significantly reducing the intrusiveness of the ultimate conduct -viewing the VIN -which, as we have said, the officers were entitled to do as part of an undoubtedly justified traffic stop.

We note that our holding today does not authorize police officers to enter a vehicle to obtain a dashboard-mounted VIN when the VIN is visible from outside the automobile. If the VIN is in the plain view of someone outside the vehicle, there is no justification for governmental intrusion into the passenger compartment to see it. *

The judgment of the New York Court of Appeals is reversed, and the case is remanded for further proceedings not inconsistent with this opinion.

It is so ordered.