Cypher, J.
The defendant, Brian Maingrette, was charged with carrying a firearm without a license, unlawful possession of ammunition, carrying a loaded firearm without a license, and receiving stolen property, after he was stopped and subsequently arrested on an outstanding warrant. He filed a motion to suppress, arguing that his arrest was invalid because the warrant on which it was based had been recalled and, therefore, the incriminating items found in the trunk of his motor vehicle that were the basis for the pending charges must be suppressed. After a hearing, a [692]*692judge of the Boston Municipal Court allowed the motion. The Commonwealth sought leave from a single justice of the Supreme Judicial Court to pursue an interlocutory appeal of that ruling. The single justice allowed the Commonwealth’s application and directed the appeal to the Appeals Court.
Motion hearing. Boston police Officer John Burrows was the only witness to testify at the suppression hearing. Because the motion judge’s findings are soundly based on Burrows’s testimony and are not in dispute, we quote from them here.
“On September 10,2012, officers assigned to the Youth Violence Task Force received information from a superior officer within the Boston [pjolice department that the defendant had been involved in a domestic incident the night before and he had brandished a gun. The defendant was known to the officers of the Youth Violence Task Force due to prior criminal investigations.
“Officer Burrows checked the warrant management system at 1:00 p.m. on September 10th and learned that the defendant had failed to appear that same morning in Middlesex Superior Court on a charge of armed assault with intent to murder. A default warrant had issued for his arrest. The officer printed a copy of the warrant.
“Officer Burrows and fellow officers went to an address where the defendant’s mother resides and where the defendant was known to frequent. The defendant was not located. They then traveled to 150 Edgemere Road, apartment 11, in West Roxbury. This was the address listed on the defendant’s driver’s license. At approximately 2:40 p.m., the police arrived at the targeted apartment and knocked on the door. No one answered. Two detectives set up a surveillance of the apartment from an unmarked police vehicle. Officer Burrows left the area and returned to the police headquarters for the Youth Violence Task Force unit in Dorchester.
“At about 4:15 p.m., the defendant was observed by the detectives driving a silver Acura [automobile] on Edgemere Road. Police observed him park his vehicle, exit[,] and enter the targeted apartment. Officer Burrows was notified of the presence of the defendant and he returned from headquarters to 150 Edgemere Road with other members of his unit. Their [693]*693purpose was to arrest the defendant on the warrant that they believed was still outstanding.”
We pause in our recitation of the judge’s findings to note that Officer Burrows, who was the sole witness at the hearing and whose testimony is not disputed (see Commonwealth v. Isaiah I., 448 Mass. 334, 337-338 [2007], S.C., 450 Mass. 818, 819-821 & n.4 [2008]), testified in addition that by 4:30 p.m. at least seven officers had returned to the area and were “just waiting for transmissions” from the two detectives who had remained behind and were still watching the residence. Each officer had access to the warrant management system (WMS)1 through a computer in each of the police vehicles in which they were traveling. The judge’s written findings of fact continue as follows.
“At 5:00 p.m., the defendant left his home, entered his vehicle and began driving on Edgemere Road. Police blocked the vehicle and ordered the defendant to exit with his hands shown. The defendant did not obey the order. Police approached him with their guns drawn. The defendant eventually complied .... He was placed under arrest.
“When police searched the trunk of his vehicle, they found a loaded firearm wrapped in a towel. Two [iP]hones and $940 . . . were found in the glove compartment.
“During the booking procedure at the police station, officers found a default removal form on the defendant’s person. The form revealed that the defendant had reported to Middlesex Superior Court that afternoon. The default warrant had been recalled at 3:00 p.m. and the defendant was no longer on default status.2 When police asked the defendant why he had not informed police of the recalled warrant, he told them they had never asked him.”
[694]*694In addition to the evidence summarized in these findings, a 1995 Boston police policy (special order number 95-31) was admitted in evidence. This policy in pertinent part states, “Immediately prior to arresting a person for an outstanding warrant, officers shall notify Operations so that the computerized Warrant Management System can be checked to determine if the outstanding warrant is still active . . . . ”
Based on this evidence, the motion judge ruled that the two detectives who were conducting stationary surveillance of the defendant’s apartment for more than two hours; Officer Burrows, who had returned to headquarters; and the other officers who were part of the team and equipped with computers had ample time and opportunity to check the status of the defendant’s default warrant before arresting him. The motion judge concluded that their failure to do so, in violation of the police department’s own policy, rendered the ensuing stop and search of his vehicle unlawful and in violation of the defendant’s constitutional rights under the Fourth Amendment to the United States Constitution and art. 14 of the Massachusetts Declaration of Rights.
Discussion. On appeal, the Commonwealth does not dispute that had the officers checked the WMS in the minutes immediately preceding the defendant’s arrest, they would have discovered that the arrest warrant was no longer valid. Nor is there any dispute that, absent the warrant, there was no independent basis for the arrest. The Commonwealth contends, however, that the police reliance upon information obtained from the WMS about four hours before the arrest was reasonable. The Commonwealth argues that, based on the officers’ experience, there was no good reason for the officers to suspect that the defendant had cleared the warrant after 1:00 p.m. and the defendant did not inform the officer of the recall when stopped and placed under arrest. Because the “delay in obtaining the updated information was reasonable,” and art. 14 “is not violated by reasonable mistakes of fact,” Commonwealth v. Porter P., 456 Mass. 254, 270 (2010), the Commonwealth argues, probable cause existed at the time of arrest and exclusion is not an appropriate remedy.
In reviewing a judge’s ruling on a motion to suppress, “we accept the judge’s subsidiary findings of fact absent clear error ‘but conduct an independent review of his ultimate findings and conclusions of law.’ ” Commonwealth v. Scott, 440 Mass. 642, 646 (2004), quoting from Commonwealth v. Jimenez, 438 Mass. 213, 218 (2002).
[695]
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Cypher, J.
The defendant, Brian Maingrette, was charged with carrying a firearm without a license, unlawful possession of ammunition, carrying a loaded firearm without a license, and receiving stolen property, after he was stopped and subsequently arrested on an outstanding warrant. He filed a motion to suppress, arguing that his arrest was invalid because the warrant on which it was based had been recalled and, therefore, the incriminating items found in the trunk of his motor vehicle that were the basis for the pending charges must be suppressed. After a hearing, a [692]*692judge of the Boston Municipal Court allowed the motion. The Commonwealth sought leave from a single justice of the Supreme Judicial Court to pursue an interlocutory appeal of that ruling. The single justice allowed the Commonwealth’s application and directed the appeal to the Appeals Court.
Motion hearing. Boston police Officer John Burrows was the only witness to testify at the suppression hearing. Because the motion judge’s findings are soundly based on Burrows’s testimony and are not in dispute, we quote from them here.
“On September 10,2012, officers assigned to the Youth Violence Task Force received information from a superior officer within the Boston [pjolice department that the defendant had been involved in a domestic incident the night before and he had brandished a gun. The defendant was known to the officers of the Youth Violence Task Force due to prior criminal investigations.
“Officer Burrows checked the warrant management system at 1:00 p.m. on September 10th and learned that the defendant had failed to appear that same morning in Middlesex Superior Court on a charge of armed assault with intent to murder. A default warrant had issued for his arrest. The officer printed a copy of the warrant.
“Officer Burrows and fellow officers went to an address where the defendant’s mother resides and where the defendant was known to frequent. The defendant was not located. They then traveled to 150 Edgemere Road, apartment 11, in West Roxbury. This was the address listed on the defendant’s driver’s license. At approximately 2:40 p.m., the police arrived at the targeted apartment and knocked on the door. No one answered. Two detectives set up a surveillance of the apartment from an unmarked police vehicle. Officer Burrows left the area and returned to the police headquarters for the Youth Violence Task Force unit in Dorchester.
“At about 4:15 p.m., the defendant was observed by the detectives driving a silver Acura [automobile] on Edgemere Road. Police observed him park his vehicle, exit[,] and enter the targeted apartment. Officer Burrows was notified of the presence of the defendant and he returned from headquarters to 150 Edgemere Road with other members of his unit. Their [693]*693purpose was to arrest the defendant on the warrant that they believed was still outstanding.”
We pause in our recitation of the judge’s findings to note that Officer Burrows, who was the sole witness at the hearing and whose testimony is not disputed (see Commonwealth v. Isaiah I., 448 Mass. 334, 337-338 [2007], S.C., 450 Mass. 818, 819-821 & n.4 [2008]), testified in addition that by 4:30 p.m. at least seven officers had returned to the area and were “just waiting for transmissions” from the two detectives who had remained behind and were still watching the residence. Each officer had access to the warrant management system (WMS)1 through a computer in each of the police vehicles in which they were traveling. The judge’s written findings of fact continue as follows.
“At 5:00 p.m., the defendant left his home, entered his vehicle and began driving on Edgemere Road. Police blocked the vehicle and ordered the defendant to exit with his hands shown. The defendant did not obey the order. Police approached him with their guns drawn. The defendant eventually complied .... He was placed under arrest.
“When police searched the trunk of his vehicle, they found a loaded firearm wrapped in a towel. Two [iP]hones and $940 . . . were found in the glove compartment.
“During the booking procedure at the police station, officers found a default removal form on the defendant’s person. The form revealed that the defendant had reported to Middlesex Superior Court that afternoon. The default warrant had been recalled at 3:00 p.m. and the defendant was no longer on default status.2 When police asked the defendant why he had not informed police of the recalled warrant, he told them they had never asked him.”
[694]*694In addition to the evidence summarized in these findings, a 1995 Boston police policy (special order number 95-31) was admitted in evidence. This policy in pertinent part states, “Immediately prior to arresting a person for an outstanding warrant, officers shall notify Operations so that the computerized Warrant Management System can be checked to determine if the outstanding warrant is still active . . . . ”
Based on this evidence, the motion judge ruled that the two detectives who were conducting stationary surveillance of the defendant’s apartment for more than two hours; Officer Burrows, who had returned to headquarters; and the other officers who were part of the team and equipped with computers had ample time and opportunity to check the status of the defendant’s default warrant before arresting him. The motion judge concluded that their failure to do so, in violation of the police department’s own policy, rendered the ensuing stop and search of his vehicle unlawful and in violation of the defendant’s constitutional rights under the Fourth Amendment to the United States Constitution and art. 14 of the Massachusetts Declaration of Rights.
Discussion. On appeal, the Commonwealth does not dispute that had the officers checked the WMS in the minutes immediately preceding the defendant’s arrest, they would have discovered that the arrest warrant was no longer valid. Nor is there any dispute that, absent the warrant, there was no independent basis for the arrest. The Commonwealth contends, however, that the police reliance upon information obtained from the WMS about four hours before the arrest was reasonable. The Commonwealth argues that, based on the officers’ experience, there was no good reason for the officers to suspect that the defendant had cleared the warrant after 1:00 p.m. and the defendant did not inform the officer of the recall when stopped and placed under arrest. Because the “delay in obtaining the updated information was reasonable,” and art. 14 “is not violated by reasonable mistakes of fact,” Commonwealth v. Porter P., 456 Mass. 254, 270 (2010), the Commonwealth argues, probable cause existed at the time of arrest and exclusion is not an appropriate remedy.
In reviewing a judge’s ruling on a motion to suppress, “we accept the judge’s subsidiary findings of fact absent clear error ‘but conduct an independent review of his ultimate findings and conclusions of law.’ ” Commonwealth v. Scott, 440 Mass. 642, 646 (2004), quoting from Commonwealth v. Jimenez, 438 Mass. 213, 218 (2002).
[695]*695Several Massachusetts appellate cases shed light on the appropriate analysis to be applied when reliance by a police officer on mistaken information to justify a search or seizure, as here, is the officer’s responsibility alone. First, in Commonwealth v. Hecox, 35 Mass. App. Ct. 277 (1993), we reversed a defendant’s conviction of trafficking in cocaine where a police officer mistakenly believed that an arrest warrant for the defendant was outstanding — even though it had been rendered obsolete five days earlier — because the officer either “did not check with his communications officer or he received incorrect data until the time he arrested the defendant.” Id. at 281. Deciding the matter solely under Federal law, id. at 282, we held that, where police have “stale information or outmoded records that are demonstrably incorrect, the government has the burden of showing that it is not at fault in failing to update its records or to provide correct information.” Id. at 284. Because the Commonwealth failed to meet this burden, we concluded that the defendant’s motion to suppress evidence should have been allowed. Id. at 285. This court stated in Hecox, “ ‘[T]he police may not rely upon incorrect or incomplete information when they are at fault in permitting the records to remain uncorrected’ or at fault in not informing themselves.” Id. at 284, quoting from 2 LaFave, Search and Seizure § 3.5(d), at 21-22 (2d ed. 1987).
Similarly, in Commonwealth v. Censullo, 40 Mass. App. Ct. 65, 69-70 (1996), we concluded that the exclusionary rule required suppression of evidence on Federal constitutional grounds when an officer’s ignorance of traffic logistics at an intersection on his patrol route resulted in the defendant’s arrest. Rejecting the Commonwealth’s contention that the officer’s mistake ought to be excused because he was acting in good faith, an exception to the exclusionary rule Massachusetts has not adopted,3 we instead balanced whether the violation was substantial and prejudicial and [696]*696the extent to which exclusion would deter future violations and concluded the evidence obtained as a result of the stop must be suppressed. Id. at 67-70.
Recently, in Commonwealth v. Hernandez, 456 Mass. 528, 528-530 (2010), the Supreme Judicial Court ruled that heroin and cocaine seized by Boston University police officers during a motor vehicle stop outside of their jurisdiction was properly suppressed. Because the arrest was made without statutory or common-law authority, the court viewed it as an invalid exercise of official power “closely associated with the constitutional right to be free from unreasonable searches and seizures,” id. at 532, quoting from Commonwealth v. LeBlanc, 407 Mass. 70,75 (1990), and thus the items seized were subject to the exclusionary rule. Commonwealth v. Hernandez, supra at 532-533. See Commonwealth v. Hampton, 457 Mass. 152,155 (2010) (exclusionary rule applies to intentional deprivation of statutory right to use telephone). The violation was exacerbated because the extraterritorial arrest contravened State regulations and the Boston University police department’s policy manual incorporating those regulations. Commonwealth v. Hernandez, supra at 533. Again, bypassing the contention that the evidence should not be excluded because the mistake was made in “good faith,” the court weighed the fact that the arrest without authority was a substantial violation, the “plain[ ] prejudice” resulting from the discovery of the contraband, and the likelihood that exclusion would deter the abuse of official power, and concluded that exclusion of the evidence was an appropriate remedy. Id. at 532-533.
Even more recently, in Commonwealth v. Lobo, 82 Mass. App. Ct. 803, 808-810 (2012), we concluded that despite changes in the law that rendered a police officer’s order to the driver and passengers to exit a stopped vehicle based upon the detection of odor of “freshly burnt marijuana” unjustified, the constitutional violation was not “so substantial and prejudicial” in the circumstances of the case as to warrant exclusion under art. 14 of the evidence seized, because in the circumstances present in the case there was no causal relationship between the order and the defendant’s ensuing arrest on outstanding warrants, and the discovery of the evidence was inevitable.
[697]*697In these cases deciding whether the application of the exclusionary rule was warranted, the foundational purpose of the rule — to deter unlawful police conduct, see, e.g., Commonwealth v. Wilkerson, 436 Mass. 137, 142 (2002) — is used as a guiding principle. In cases where an arrest is wrongly made on the basis of mistaken information chargeable solely to the police, the burden is on the government to show that it was not at fault in the circumstances, see Commonwealth v. Hecox, 35 Mass. App. Ct. at 284-285 (violation of Fourth Amendment), in other words, that the mistake was reasonable in the circumstances, and that the violation was minor or insubstantial and nonprejudicial and that exclusion of the evidence would not be likely to deter future police misconduct.4,5 See Commonwealth v. Sheppard, 394 Mass. [698]*698381, 389-391 (1985) (substantial and prejudicial requirement applied to State statutory and constitutional violations); Commonwealth v. Hernandez, 456 Mass, at 532-533 (substantial violation and prejudice found warranting application of exclusionary rule to statutory violation analogous to constitutional deprivation); Commonwealth v. Censullo, 40 Mass. App. Ct. at 67-70 (suppression of evidence on Federal constitutional grounds where stop not justified, violation substantial [officer had no legal or independent basis for stop], and exclusion will deter future violations [error was police officer’s]); Commonwealth v. Lobo, 82 Mass. App. Ct. at 808-810 (substantial and prejudicial requirement applied to art. 14 violation). See also Commonwealth v. Bel-dotti, 409 Mass. 553, 559 (1991) (testing results of occult blood from murder suspect’s hands and arms based on invalid warrant not subject to exclusion in view of minimal intrusion and likelihood of inevitable discovery).
Applying this analysis to the case at bar, the result is dictated by the circumstances preceding the arrest and the Boston police department policy.6 Specifically, the evidence shows that at various intervals during the afternoon in question there were up to nine police officers working together to locate and arrest the defendant. The assignment did not include responding to an ongoing crime in which the defendant was engaged, but rather consisted primarily of surveillance intended to locate him. Each officer in the team had access to a computer that could be used to instantly access the WMS. Added to this was testimony that between 3:00 p.m. and 5:00 p.m. two detectives remained in the neighborhood solely for the purpose of “watching [the defendant’s] residence.” When they saw the defendant return at 4:15 p.m., the detectives summonsed the other officers, including Burrows, back to the area. Burrows testified that after their arrival, “[n]othing” was happening: “We were just waiting for transmissions from the detectives watching the residence” (emphasis added). About thirty minutes later, around 5:00 p.m., the detectives alerted Burrows and the other officers that the defendant was driving away from the apartment building, and he was stopped [699]*699shortly thereafter. Given these facts, it is difficult to conclude that the police had neither the time nor the opportunity to check the WMS to confirm that the arrest warrant was still active.
This failure contravened the clear policy mandate of the Boston police department, set out in special order number 95-31, dated June 2, 1995, that “[immediately prior to arresting a person for an outstanding warrant officers shall notify Operations so that the computerized Warrant Management System can be checked to determine if the outstanding warrant is still active .... ”7 As the motion judge found, “[i]f the police had properly followed this mandate, they would have learned that the defendant was no longer on default and they were not legally authorized to stop him and search his vehicle.”
That the police department has committed to writing, for apparently the past nineteen years, the obligation of its officers to check an arrest warrant immediately before making the arrest is significant in this analysis. It signals the department’s certainty that each officer has both the ability and the technological tools to make such an inquiry. The requirement also impliedly acknowledges the rapidity with which information in the database can change and the importance of confirming such data before depriving an individual of his or her liberty. After all, the ease and speed with which a police officer may confirm the validity of an arrest warrant is an appropriate and easily executed buffer to protect the department from subsequent claims of wrongdoing, to [700]*700say nothing of an individual’s right to liberty.
In these circumstances, where the police had ample time and opportunity to comply with their own department’s policy and failed to do so, we cannot view the subsequent arrest of the defendant on an invalid warrant as reasonable. See People v. Lent, 92 A.D.2d 941 (N.Y. 1983) (arrest made on basis of warrant that had been satisfied eight hours earlier invalid; evidence seized suppressed); State v. Trenidad, 23 Wash. App. 418 (1979) (because arrest warrant had been quashed some thirty minutes before arrest, court held arrest was invalid and suppressed evidence). See also, e.g., Jenkins v. Chief Justice of the Dist. Court Dept., 416 Mass. 221, 229-231 (1993) (describing well-known purpose for adoption of art. 14, and later Fourth Amendment, as prohibiting unchecked control over liberty of people by law enforcement officers through legal devices that were accountable to no person). Moreover, that the defendant was arrested without a warrant or probable cause was clearly a substantial violation and the discovery of the inculpatory evidence was plainly prejudicial.
The order allowing the motion to suppress the evidence is affirmed.8
So ordered.