Wilkins, J.
The defendant was convicted of unlawfully carrying a firearm under his control in a motor vehicle in viola tian of G. L. c. 269, § 10 (a). Officer William Chase of the Watertown police department found the firearm in plain view when he opened the motor vehicle’s locked trunk to place eight-track tapes in it for safekeeping. He had seen the tapes in the passenger compartment of the motor vehicle which the defendant had been operating when Chase arrested him on an outstanding warrant.
Following his conviction at a bench trial in a District Court, the defendant appealed to the District Court jury session and filed a motion to suppress the rifle (and other items), alleging that the intrusion into the trunk of the motor vehicle violated his rights under the Fourteenth Amendment to the Constitution of the United States (and under the Fourth Amendment) and under art. 14 of the Declaration of Rights of the Constitution of the Commonwealth. That motion was denied. He was found guilty by ajúry and appealed to the Appeals Court. The Appeals Court reversed the conviction, holding that the intrusion into the trunk was a search for constitutional purposes and that the intrusion, which it characterized as a “storage search,” was unreasonable because it was not made pursuant to standard police procedures. Commonwealth v. Ford, 17 Mass. App. Ct. 505, 507-509 (1984). The Appeals Court left open the question whether the search would have been reasonable if it had been conducted pursuant to standard procedures. Id. at 509. We agree with the Appeals Court’s conclusions, but base our decision explicitly on State constitutional grounds.
We summarize the facts found by the motion judge and presented by Officer Chase in his testimony at the hearing on the motion to suppress. In the early hours of December 4, 1981, Officer Chase was on routine patrol in Watertown. He saw the defendant operating a motor vehicle and, aware that there was an arrest warrant outstanding against the defendant, stopped the vehicle. The defendant, who was alone, produced a license but no registration. He told Officer Chase that he was waiting for title on the vehicle before registering it. Officer Chase arrested the defendant and took him to the police station, where Officer Chase learned from the Registry of Motor Vehi des that the vehicle was unregistered. He decided to remove the vehicle from the street where, because of the coincidence of where it had been stopped, it was parked in a restricted area. A private tow truck was called, and the officer returned to the motor vehicle.
Because he knew that personal property had been stolen from vehicles that had been towed and stored by the private tow company, the officer reached into the vehicle to secure its contents. As he removed the ignition key from the defendant’s key ring, Office Chase noticed eight-track tapes on the seat and on the floor of the passenger side of the vehicle. He opened the locked trunk in order to place the tapes in the trunk and saw the rifle. Office Chase testified that the Watertown police department did not have any specific procedure for securing property found in a vehicle that was about to be towed, but that, unless it was particularly valuable, most officers placed personal property seen in a vehicle’s passenger compartment in the trunk, left the ignition key with the car, and took all other keys to the station.
The motion judge concluded that Officer Chase did not intend to search the vehicle, that he did not expect to find contraband, that he had a legitimate reason for opening the trunk, and that the rifle was in plain view. He accordingly denied the motion to suppress.
1. The Commonwealth argues that there was no search in the constitutional sense because Officer Chase was not looking for anything when he opened the trunk of the motor vehicle. See State v. Tully, 166 Conn. 126, 131-133 (1974); Model Code of Pre-Arraignment Procedure § SS 210.1 (1) (1975). We reject this argument and agree with the Appeals Court that, whatever a police officer’s intentions may be, when he intrudes into an area in which a person had a reasonable expectation of privacy, it is a search for constitutional purposes. “In our view the sounder course is to recognize that the Fourth Amendment [and art. 14 govern] all intrusions by agents of the public upon personal security, and to make the scope of the particular intrusion, in light of all the exigencies of the case, a central element in the analysis of reasonableness. . . . This seems preferable to an approach which attributes too much significance to an overly technical definition of ‘search. ’ ” Terry v. Ohio, 392 U.S. 1, 17-18 n.15 (1968). Thus a search occurs whenever “an expectation of privacy that society is prepared to consider reasonable” is infringed. United States v. Jacobsen, 466 U.S. 109, 122 (1984). We think there was a search for the purposes of the Fourth Amendment. Commonwealth v. Ford, 17 Mass. App. Ct. at 507, and authorities cited. We hold, in any event, that it was a search for the purposes of art. 14 of the Declaration of Rights. The officer’s state of mind may be significant in determining whether the search was reasonable or unreasonable, but it is not significant in determining whether there was a search in this case.
2. We turn then to the question of the reasonableness of the intrusion. The parties have discussed by analogy cases involving inventory searches. In South Dakota v. Opperman, 428 U.S. 364 (1976), the Supreme Court of the United States upheld the seizure of contraband found in the course of an inventory search, pursuant to standard police procedures, of the unlocked glove compartment of a locked, impounded motor vehicle. The Court stated generally that “inventories pursuant to standard police procedures are reasonable,” id. at 372, and noted, in discussing Cady v. Dombrowski, 413 U.S. 433, 436 (1973), that “the protective search was carried out in accordance with standard procedures in the local police department, . . . a factor tending to ensure that the intrusion would be limited in scope to the extent necessary to carry out the caretaking function,” South Dakota v. Opperman, supra at 374-375 (emphasis in original). Similarly, in his concurring opinion in the Opperman case, Justice Powell emphasized that, when “[inventory searches are conducted in accordance with established police department rules or policy,” officers cannot “make a discretionary determination to search” and “there is no significant danger of hindsight justification.” Id. at 383 (Powell, J., concurring). We have also noted the importance of standard police procedures when an inventory search is conducted, Commonwealth v. Wilson, 389 Mass. 115, 117 (1983); Commonwealth v. Matchett, 386 Mass. 492, 510 (1982), and have suggested that a particular inventory search of a vehicle’s trunk conducted in accordance with standard police procedures may have been resonable under the Fourth Amendment. See Commonwealth v. Hason, 387 Mass. 169, 178 (1982).
We need not decide whether the same principles apply to storage searches and inventory searches. There are, however, differences between the two procedures. Nor need we decide whether the motion judge was correct in concluding that the particular circumstances of the storage search of the trunk were reasonable. We agree instead with the Appeals Court that, to be lawful, any such search must at least be conducted according to standard procedures established by the police department. Because there is no basis on this record in this case for finding that the storage search in this case was conducted pursuant to standard procedures established by the Watertown police department, we conclude that the search was unreasonable.
There may be some question whether an inventory or storage search of the locked trunk of a vehicle impounded on a public way must be conducted pursuant to standard police procedures in order to meet the requirements of the Fourth Amendment. We, therefore, state, as a separate, adequate, and independent ground, that such a search must at least be made pursuant to such procedures in order to satisfy art. 14 of the Declaration of Rights.
We are thus holding that art. 14 of the Declaration of Rights requires the exclusion of evidence seized during a storage search not conducted pursuant to standard police procedures. We have recently considered claims of exclusion based on art. 14 but in the circumstances did not have to decide whether violations of art. 14 required the exclusion of evidence. See Commonwealth v. Upton, ante 363, 365-366 (1985). Cf. Selectmen of Framingham v. Municipal Court of the City of Boston, 373 Mass. 783, 787-788 (1977) (civil case; evidence excluded as a matter of Massachusetts law). We have consistently noted in recent years the possibility that art. 14 affords more substantive protection to criminal defendants than prevails under the Constitution of the United States. Commonwealth v. Upton, supra at 373, and cases cited. In Commonwealth v. Sheppard, ante 381, 391 (1985), we concluded on the facts that a violation of art. 14 did not require exclusion of evidence. This case, however, involves circumstances in which art. 14 requires exclusion of evidence. We suspect the Supreme Court of the United States would reach the same conclusion under the Fourth Amendment.
A warrantless search conducted without consent, without probable cause, and without exigent circumstances justifying the intrusion (such as protection against potential danger), but conducted pursuant to standard procedures, will have a greater chance of meeting constitutional requirements than an ad hoc practice such as is involved in this case. A search pursuant to standard procedures will eliminate any element of discretion in the decision to conduct an inventory or a storage search. We do not decide, however, or imply that, if a storage search is conducted pursuant to standard police procedures, evidence seized in the search will be admissible.
3. The motion to suppress should have been allowed. The judgment is reversed, and the verdict set aside. It may be that the defendant is entitled to entry of a judgment of not guilty. The case is remanded to the District Court for consideration of that question.
So ordered.
This case does not involve an entry into an impounded vehicle either to secure the vehicle or to secure property in plain view with the resulting discovery of other property in plain view within the passenger compartment. In such a case, that other property could be seized reasonably and its admission in evidence would be proper. See Harris v. United States, 390 U.S. 234, 236 (1968) (evidence in plain view seized in securing an impounded vehicle, admissible); State v. Tully, 166 Conn. 126, 136-137 (1974) (evidence found in plain view on entering a vehicle with a broken window to remove personal property for safekeeping, admissible). If, for example, Officer Chase had found a rifle in plain view inside the passenger compartment of the vehicle when he entered it to remove keys and subsequently to secure the tapes, the seizure of the rifle would have been constitutionally proper. In the case before us, however, we are concerned with an intrusion into a locked trunk.
The question whether an inventory search of a locked trunk is constitutionally permissible has not expressly been answered by the Supreme Court of the United States and has been variously answered by other courts. See South Dakota v. Opperman, supra at 385 n.1 (Marshall, J., dissenting). Compare United States v. Wilson, 636 F.2d 1161, 1163-1165 (8th Cir. 1980) (may not inventory trunk), with United States v. Edwards, 577 F.2d 883, 893-894 & n.23 (5th Cir.), cert. denied, 439 U.S. 968 (1978), and United States v. Martin, 566 F.2d 1143, 1145 (10th Cir. 1977) (allowing trunk inventories when made pursuant to standard procedures). Some State courts have dealt with the question of trunk inventories under their own Constitutions and have arrived at different conclusions. Compare State v. Sawyer, 174 Mont. 512, 517-518 (1977) (no trunk inventories), State v. Opperman, 247 N.W.2d 673 , 675 (S.D. 1976) (safeguarding permitted only of articles in plain view), and State v. Goff, 166 W.Va.
n.7 (1980) (272 S.E.2d 457, 460, 462 n.7 [W.Va. 1980]) (no trunk inventories), with State v. Fortune, 236 Kan. 248, 256-258 (1984), and State v. Prober, 98 Wis. 2d 345, 351, 353-355 (1980) (inventory search of trunks permissible). There is no need to decide in this case whether the Fourth Amendment or art. 14 prohibits generally an inventory or storage search of a vehicle’s trunk.
One difference, as we have noted, is the purpose of the police officer’s intrusion. Additionally, the need to open a locked trunk differs in the two situations. In this case, there was no need to open the locked trunk in order to secure the tapes, and thus that intrusion may well have been less reasonable than in a case in which the opening of a locked trunk is necessary to conduct an inventory search. The defendant’s key ring had to be taken to the police station, and it is unclear on this record why the tapes could not have gone along with the key ring.
The dissent surprisingly faults the court for not espousing standards on which its decision is based. We have indicated standards and the basis for exclusion of the evidence in this case. This was a warrantless search. Searches pursuant to a search warrant present different questions concerning the exclusion of evidence. Here, there was neither probable cause to search nor any special circumstances, such as an emergency, to justify a warrantless search without probable cause. However the dissent may view the matter, the fact remains that in an inventory search a vehicle’s trunk has to be opened and in a storage search it does not. If a storage search is to be constitutionally reasonable, action pursuant to established police procedures seems appropriately required. We see no reason to “decide” a case not before us, and thus we leave open the question of the constitutionality of a storage search conducted pursuant to established police procedures.