On July 2 and 3, 1983, State police officers conducted a roadblock on Route 116 in Sunderland. Each of the three defendants was stopped at the roadblock and, subsequently, arrested and charged with operating a motor vehicle while under the influence of alcohol. G. L. c. 90, § 24 (1984 ed.). Each defendant moved to suppress evidence obtained as a result of the roadblock, alleging violations of his rights under both the United States Constitution and the Declaration of Rights of the Massachusetts Constitution. The motion judge denied these motions. He made no findings of fact. The defendants appealed, and filed a petition to transfer the case to the Supreme Judicial Court for Suffolk County. The parties cooperated with the single justice, agreed on the facts, and framed the questions. After a hearing, a single justice reserved and reported the following questions to this Court:
“1. Were guidelines promulgated by the Secretary of Public Safety to govern drunk driving roadblocks properly promulgated and did they make adequate provisions so as not to offend the guarantees of the Fourth and Fourteenth Amendments to the United States Constitution, Articles 12 and 14 of the Massachusetts Declaration of Rights and Massachusetts General Laws, Chapter 41, Section 98?2
*83“2. If the answer to Question 1 is in the affirmative, was the roadblock conducted on July 2nd and July 3rd, 1983 on Route 116 in Sunderland, executed in substantial compliance with the guidelines promulgated by the Secretary of Public Safety so as not to offend the guarantees of the Fourth and Fourteenth Amendments to the United States Constitution, Articles 12 and 14 of the Massachusetts Declaration of Rights and Massachusetts General Laws, Chapter 41, Section 98?
“3. If the answer to Question 2 is in the affirmative, would a future roadblock conducted in substantial compliance with the guidelines in this case but without any notice or publicity still not offend the guarantees of the Fourth and Fourteenth Amendments to the United States Constitution, Articles 12 and 14 of the Massachusetts Declaration of Rights, and Massachusetts General Laws, Chapter 41, Section 98?”
For the reasons set forth below, we answer “Yes” to Questions 1 and 2 as we interpret them. We choose not to address the issues presented by Question 3. We have reproduced the guidelines in an Appendix to this opinion.
1. Factual background. The facts, as agreed upon by the parties, may be summarized as follows.
A. Development and dissemination of the guidelines. In March of 1983, the Governor of the Commonwealth and Charles V. Barry, Secretary of Public Safety of the Commonwealth, decided to implement a series of roadblocks in an attempt to deter drunk driving. Lieutenant Thomas K. Kennedy, the head of Research and Development for the State Police, in consultation with several individuals and organizations,3 created a set of guidelines relative to roadblocks. The guidelines were developed with a view toward compliance with this court’s opinion in Commonwealth v. McGeoghegan, 389 Mass. 137 (1983). The guidelines were never officially promulgated as certain regulations are required to be promul*84gated. See generally G. L. c. 30A, §§ 2-3 (State Administrative Procedure Act).
On May 20, 1983, Secretary Barry’s office decided that the first such roadblocks would be conducted on the upcoming July fourth weekend. On June 28, 1983, a training session was held at the State Police Academy. Captain James Port, Commanding Officer of the State Police Traffic Bureau, conducted the session, which was intended to train those in attendance to implement the guidelines at roadblocks to be conducted during the July fourth weekend. Those invited to the training session included the heads of all the State police troops in the Commonwealth, as well as their assistants. Each person who attended the session received a copy of the guidelines.
At this training session, Port emphasized that there should be no deviations from the guidelines while the roadblocks were being conducted. If an emergency occurred, any change in the procedures set forth in the guidelines would have to be made by the supervising officer.
A second training session took place at the Academy on June 30, 1983. At this session, a demonstration roadblock was conducted in accordance with the instructions provided at the June 28 session. Those attending the sessions were told that the following criteria were to be applied in selecting a roadblock site: high accident rates, high rates of drunk driving arrests, safety conditions, and motorist convenience.
B. The Sunderland roadblock. Captain Thomas J. Fitzgerald, the captain in charge of the State police in Western Massachusetts, accompanied by several assistants, attended the June 28 training session. Captain Fitzgerald also attended the June 30 session. He chose the site for the Sunderland roadblock, which was conducted on Route 116. The Route 116 patrol area is a high fatality area, and one with a high rate of drunk driving arrests.
The roadblock detail began at 7 p.m. on July 2, 1983. Thirteen uniformed State police officers, including Captain Fitzgerald and one other officer who had attended the June 28 training session, took part in the roadblock. Each trooper received approximately one hour of training, during which Fitz*85gerald explained the procedures set forth in the guidelines. Fitzgerald trained the troopers as he had been instructed at the two training sessions at the Academy. The roadblock was conducted in a manner consistent with the training of Fitzgerald.
The troopers were instructed to stop every automobile as it approached the roadblock site, but to allow trucks and tractor-trailer units to pass through the roadblock without stopping. They were told that the initial contact would be no more than one minute for each individual operator. During that brief period, the troopers were to say “Good evening, how are you, this is a State Police sobriety checkpoint, we would like you to have a copy of the brochure on drunk driving laws.” If the troopers saw no problems, they were to say “Thank you,” and allow the vehicle to proceed. The actual stopping time at the roadblock was approximately thirty seconds. During that period, the trooper was instructed to observe the operator, as well as the interior of the vehicle, to determine if there was any suspicion that the operator had been drinking.
If the trooper suspected that the operator had been drinking, the trooper was to instruct the operator to drive to a detention area. Unless the operator was extremely intoxicated, he or she would be permitted to drive the vehicle into this area. In the detention area, a driver would be asked to produce a license and registration, and to perform three field sobriety tests.
The roadblock began at approximately 11:30 p.m. on July 2, 1983, and ended at approximately 2 a.m. on July 3, 1983. Five hundred and three vehicles approached the roadblock. Each was stopped. Sixteen operators were detained for further checks. Eight operators, including the three defendants, were arrested.
C. Publicity. Prior to the July fourth weekend, information concerning the upcoming roadblocks was provided to the news media, including television, radio, and print. Secretary Barry and Captain Fitzgerald both spoke to members of the media. The public relations office of the State Police distributed press releases to over four hundred news media affiliates within the State. Several newspapers, radio stations, and television stations in Hampshire County disseminated information about the roadblocks both prior to and during the holiday weekend.
*862. Constitutional setting. We note that, “[although the Massachusetts Declaration of Rights may afford greater protection to an individual than the protection afforded by the United States Constitution, ... the same factors are material to a consideration of the constitutionality under either document of a roadblock stop of motor vehicles for the purpose of detecting drunk drivers” (citations omitted). Commonwealth v. McGeoghegan, supra at 141 n.2. It is well established that the stopping of each defendant’s motor vehicle was a seizure within the Fourth and Fourteenth Amendments to the United States Constitution. Delaware v. Prouse, 440 U.S. 648, 653-654 (1979). Our inquiry becomes, therefore, whether the seizures were reasonable. McGeoghegan, supra at 139. Accordingly, we must balance the public interest against “the individual’s right to personal security free from arbitrary interference by law officers.” United States v. Brignoni-Ponce, 422 U.S. 873, 878 (1975). Some courts have thought it important in a constitutional sense that the prosecution demonstrate that, in dealing with the problem of drunk drivers, there is no alternative to roadblocks that would be as effective as, and less intrusive than, roadblocks. See State v. Superior Court, 143 Ariz. 45 (1984); State v. Deskins, 234 Kan. 529, 541 (1983); State v. Koppel, 127 N.H. 286, 291-292 (1985). We construe the questions asked of us as not raising this issue or the underlying question whether, for constitutional purposes, it matters whether there may be a less intrusive but equally effective means of dealing with the problem. Our construction of these questions is consistent with the views of the parties, who have not argued these points.
Clearly there exists a strong public interest in reducing the “carnage caused by drunk drivers.” South Dakota v. Neville, 459 U.S. 553, 558 (1983). We take notice that traditional methods of law enforcement in this area have failed. Each year, over 25,000 people die in traffic accidents in which alcohol consumption is involved. H.R. Rep. No. 867, 97th Cong., 2d Sess. 7, reprinted in 1982 U.S. Code Cong. & Ad. News 3367. This total represents approximately half of the deaths resulting from motor vehicle accidents which occur on *87our nation’s roads each year. Id. In addition, over the past ten years more than one million people have received serious injuries in accidents involving drunken drivers. Massachusetts Senate Committee on Post Audit and Oversight, Drinking and Driving in Massachusetts: Statutory Options and Recommendations 1 (1982). Studies suggest that, on any weekend night in Massachusetts, between five and ten per cent of all drivers on the road will be seriously impaired by alcohol. Id.
In McGeoghegan, we considered whether a roadblock designed to detect drunk drivers could be conducted in a manner that would be constitutionally permissible. After considering relevant Supreme Court decisions in the area, we suggested that for a roadblock to be permissible, “the selection of motor vehicles to be stopped must not be arbitrary, safety must be assured, motorists’ inconvenience must be minimized and assurance must be given that the procedure is being conducted pursuant to a plan devised by law enforcement supervisory personnel.” McGeoghegan, supra at 143. We further suggested that advance notice of an intended roadblock, although perhaps not constitutionally mandated, would be appropriate because it would “have the virtue of reducing surprise, fear, and inconvenience.” Id. We remain of the opinion that the above standards are relevant to any analysis of the validity of a roadblock procedure under both the State and Federal Constitutions.
Cases from other States which have considered roadblocks executed under guidelines are supportive. See, e.g., Stark v. Perpich, 590 F. Supp. 1057 (D. Minn. 1984); State v. Golden, 171 Ga. App. 27 (1984); Little v. State, 300 Md. 485 (1984). Cf. State ex rel. Ekstrom v. Justice Court, 136 Ariz. 1 (1983).
3. Question 1: “Were guidelines promulgated by the Secretary of Public Safety to govern drunk driving roadblocks properly promulgated and did they make adequate provisions so as not to offend the guarantees of the Fourth and Fourteenth Amendments to the United States Constitution, Articles 12 and 14 of the Massachusetts Declaration of Rights and Massachusetts General Laws, Chapter 41, Section 98?”
*88Promulgation of the guidelines.4 The defendants argue that the roadblock guidelines constituted “regulations” as that word is defined in G. L. c. 30A, § 1 (5) (1984 ed.),5 and that therefore the guidelines are invalid because they were not promulgated as required by the State Administrative Procedure Act. See G. L. c. 30A, §§ 2-6. The defendants claim that the guidelines were of no effect and, consequently, the defendants’ arrests constituted a denial of due process and a violation of their constitutional rights.
The defendants argue that the guidelines are of “general application,” and thus fall within the purview of the Act. Determining whether a particular guideline or pronouncement constitutes a “regulation” under the Act may be a difficult task.6 The language of the definition reflects an intent that it be interpreted broadly. See Curran & Sacks, The Massachusetts Administrative Procedure Act, 37 B.U.L. Rev. 70, 77 (1957). We conclude that these guidelines did not constitute a regulation.
*89The guidelines concern the “internal management” of the State police department, and thus they fall within the exemption from the definition of a regulation by clause (b) of § 1 (5). We reject the defendants’ interpretation of clause (b) as only applicable to rules concerning the organizational structure of an agency. The guidelines are directed solely toward troopers, and instruct them as to the manner in which they are to fulfil their duties. Thus, they do concern the internal management of this agency.
Clause (b) only applies to regulations that do not “substantially affect [ ] the rights of or the procedures available to the public . . . .” The guidelines describe the purpose and operational philosophy underlying the use of roadblocks. They limn important procedural and safety considerations. The guidelines reflect an attempt to ensure that the State police execute roadblocks in compliance with the principles articulated in Commonwealth v. McGeoghegan, supra. They do not purport directly to regulate public conduct. The guidelines are simply an accurate reflection of the rights of the public as set forth in McGeoghegan. We conclude that the guidelines are not regulations as defined in G. L. c. 30A, § 1 (5).
We turn to the roadblock procedures contained in the guidelines. The guidelines clearly proscribe the arbitrary selection of vehicles to be stopped. Ample provision is made to assure that the roadblock is conducted safely, including clear directions on the manner in which the sites should be selected and set up. The guidelines also address the element of motorist inconvenience, both with respect to traffic congestion and the brief nature of the initial stop. Furthermore, the guidelines require that a roadblock be planned in advance by supervisory personnel. The plans must include “date, location, time, duration, and set patterns of cars to be stopped.” Finally, the guidelines provide that the supervisors will announce the date of an intended roadblock to the news media, at best three days prior to its implementation.
The guidelines at issue clearly comport with the McGeoghe-gan principles. Balancing the procedures against the public’s interest in curtailing drunk driving, we conclude (without decid*90ing whether a roadblock is the least restrictive means or whether use of the least restrictive means is constitutionally required) that a seizure made in the course of a roadblock which is carried out pursuant to the guidelines would be reasonable under both the State and Federal Constitutions.
4. Question 2: “If the answer to Question 1 is in the affirmative, was the roadblock conducted on July 2nd and July 3rd, 1983 on Route 116 in Sunderland, executed in substantial compliance with the guidelines promulgated by the Secretary of Public Safety so as not to offend the guarantees of the Fourth and Fourteenth Amendments to the United States Constitution, Articles 12 and 14 of the Massachusetts Declaration of Rights and Massachusetts General Laws, Chapter 41, Section 98?”
The Commonwealth bears the burden of proving the lawfulness of the Sunderland roadblock. Commonwealth v. An-tobenedetto, 366 Mass. 51, 57 (1974). The roadblock was conducted pursuant to a plan developed by State police supervisory personnel. The parties agree that “[t]he roadblock was conducted consistent with the training of Captain Fitzgerald,” who had received instruction at two roadblock training sessions. Captain Fitzgerald chose the roadblock site, following the criteria set forth in the guidelines. Publicity preceding the roadblock included stories on the television and radio, as well as thirteen newspaper articles.
Thirteen uniformed State troopers were present at the roadblock site. Five hundred feet before the stopping area there was placed a four by five foot reflectorized sign which read “Stop Ahead” “Roadblock.” A safety cruiser with all of its lights illuminated was positioned directly across from the sign. Safety flares were placed throughout the roadblock area. A second sign and five flares were placed three hundred feet from the stopping point. Four cruisers were parked close to the stopping area. The stopping area was brightly illuminated by lights from a police van.
The troopers were instructed to stop every automobile that approached the site. Captain Fitzgerald stressed to those involved in the roadblock that there should be no deviation from the procedures set forth in the guidelines. Motorists passing *91through the roadblock were stopped for approximately thirty seconds.
In sum, the conduct of the roadblock was most reasonable and entirely responsive to the requirements and directions laid down in McGeoghegan. The news media ran numerous stories advising the public of the announcement by the authorities that at least one roadblock would be conducted by the State police somewhere within the area patrolled by the State police assigned to the Northampton barracks. They limited the time within which a motorist would be stopped. The area was lighted and the police had no discretion in the selection of motorists to be stopped. This is clearly not arbitrary and capricious conduct.
There is nothing in the statement of agreed facts to indicate that the guidelines were not carefully followed in this case.
5. Question 3: “If the answer to Question 2 is in the affirmative, would a future roadblock conducted in substantial compliance with the guidelines in this case but without any notice or publicity still not offend the guarantees of the Fourth and Fourteenth Amendments to the United States Constitution, Articles 12 and 14 of the Massachusetts Declaration of Rights, and Massachusetts General Laws, Chapter 41, Section 98?”
We choose not to address this issue. As a general rule, this court does not express an opinion on hypothetical questions involving constitutional law. Solomon v. School Comm. of Boston, 395 Mass. 12, 19 (1985). The defendant has ignored it completely and the Commonwealth’s brief has given us the benefit of only two paragraphs. We leave this constitutional question for another day. See Commonwealth v. Paasche, 391 Mass. 18, 21 (1984).
6. We answer “Yes” to Questions 1 and 2, as we have construed them. We decline to answer Question 3. The case is remanded to the county court for disposition consistent with this opinion.
*92Appendix. “MASSACHUSETTS STATE POLICE DWI ROADBLOCK ENFORCEMENT “PURPOSE: Apprehension of individuals driving while drunk or while under the influence of alcohol or drugs. “METHOD: Use of pre-selected roadblock locations conducted under the following guidelines. “OPERATIONAL PHILOSOPHY: Drunk driving roadblocks checkpoints cannot be of less public benefit than the behavior they are trying to displace, nor can they create more of a traffic hazard by their operation than the results of the driving behavior they are trying to modify. “OPERATIONAL PLANNING: Each individual roadblock must be planned in advance of actual implementation. All specifics as to the conduct of the roadblock must be preplanned and not randomly or arbitrarily implemented at the site. “PERSONNEL: Only uniformed officers who have been trained in roadblock tactics should participate. A trained supervisor must be present. “ROADBLOCK PLANS: Roadblock plans must be developed by department supervisors and disseminated to participants prior to implementation. Plans must include date, location, time, duration, and set patterns of cars to be stopped. “BASIC CONSIDERATIONS: — Selection of vehicles to be stopped must not be arbitrary. —Safety must be assured. —Motorist inconvenience must be minimized. —Action undertaken must be according to a written plan and supervised. —Advanced public notice must be given to reduce surprise, fear, and inconvenience for the motorist. “SITE SELECTION: Problem areas — where accidents or prior arrests for drunken driving have occurred. Specific areas to be selected by respective administrators and supervisors. A. Individual site selection should be based on selective enforcement identifiers as to time, place and cause of prior serious injury accidents. B. Site should allow officers to pull vehicles out of the traffic stream without causing a significant intrusion to them and/or creating a safety hazard because of a traffic back-up. It is suggested that areas adjacent to rest areas or parking lots be utilized. C. Selected sites should allow for visibility of on-coming motorists, safety for stopped vehicles, as well as safety for the officers.
*93D. Alternative sites should be pre-selected should traffic congestion occur at primary site. “SAFETY CONSIDERATIONS: Advanced warning for on-coming vehicles A. Signs (recommended) B. Sufficient roadflares to be placed on the shoulder of road. C. Police vehicles with flashing lights. D. Traffic is to be stopped by a uniformed officer, giving a visual stop signal. E. Where possible vehicles should be pulled off the road (rest area, parking lot, etc.) F. Sufficient quantity and visibility of uniformed police and cruisers to assure speedy compliance, minimize inconvenience and reduce public fear and apprehension. G. Each vehicle at the checkpoint is to be stopped for a period of one minute or less with the operator and all occupants remaining seated in the vehicle. H. No physical barriers are to be used. “ADVANCED NOTICE: Announcement of the date of the intended checkpoint, without announcing its precise location, will be made by the checkpoint supervisors to the news media at least three (3) days prior to the implementation of the checkpoint. Press releases should be structured to educate the public as to the purpose of the checkpoint, to encourage public support and to solicit cooperation. The tone of the article should provide some measure of deterrence for drunk driving. “SOBRIETY CHECKS: Inconvenience must be minimized. A. A very brief and courteous statement should be made by officers manning the checkpoints: Example — “Good evening, this is a routine sobriety checkpoint. Sorry for the inconvenience, good night.” B. Only upon observing an articulable sign of possible intoxication will further inquiry be warranted. In other words, the officer should develop at least an indication that the driver has been consuming alcohol before asking for a driver’s license or engaging in conversation regarding the consumption of alcohol. C. A supervisor must be present at all Sobriety Checkpoints and it is he/she who will decide on the setup at the location to ensure safety for all. The Supervisor will also decide: 1. The number of vehicles to be stopped (a) all vehicles (b) set number, i.e., (1) one of every ten passing cars
*94“NOTE — Random, discretionary stops, unsupported by probable cause, reasonable suspicion, or even some less stringent standard, are unreasonable and therefore, impermissible. Requests for license and registration should not be undertaken unless probable cause is determined. 2. Duration of checkpoint, not to exceed two hours unless Troop Commander requires a checkpoint exceeding that time “ARREST PROCEDURES: A. If after brief stop, the officer develops specific and articulable facts which lead the officer to believe the motorist may be intoxicated: 1. Vehicle operator requested to drive onto the shoulder of road 2. Driver requested to produce license and registration 3. Driver may be requested to perform certain motor coordination tests B. If arrested, suspect should be taken to nearest State Police Barracks for processing by arresting officer. “JUDICIAL SUPPORT: District Attorney’s [íz'c] should be contacted prior to the implementation of the roadblocks for their input into the types of evidential information that will be needed to prosecute cases. “RECORD KEEPING: Officer-in-charge of roadblock operation will insure that adequate records will be kept of each operation. Information to be collected shall include but not be limited to the following: A. Number of vehicles passing through roadblocks, i.e., total vehicles stopped or not B. Number of vehicles checked, i.e. total vehicles checked C. Number of vehicles detained for further check i.e. license and registration etc. D. All other data required on A.R. C.P. forms to be used for roadblock operation only (separate form for two hour period). E. All unusual occurrences shall be noted under remarks “NOTE Accurate records are necessary on all parts of roadblock operations in anticipation of eventual court cases.”
It is difficult to know why reference is made in all three questions to G. L. c. 41, § 98, because this statute is addressed to the powers of police officers in cities and towns. It does not reach the State Police who are governed, in the main, by G. L. c. 22.
The guidelines were developed in consultation with Secretary Barry, the Governor’s Legal Counsel, the Drunk Driving Committee of the Governor’s Anti-Crime Council, the Criminal Justice Training Council, the chief of police of Revere, and the National Highway Traffic Safety Administration.
We acknowledge the brief submitted by the Secretary of Public Safety, amicus curiae, with respect to this issue.
General Laws c. 30A, § 1 (5), provides the following definition of the term “regulation”: “(5) ‘Regulation’ includes the whole or any part of every rule, regulation, standard or other requirement of general application and future effect, including the amendment or repeal thereof, adopted by an agency to implement or interpret the law enforced or administered by it, but does not include (a) advisory rulings issued under section eight; or (b) regulations concerning only the internal management or discipline of the adopting agency or any other agency, and not substantially affecting the rights of or the procedures available to the public or that portion of the public affected by the agency’s activities; or (d) regulations relating to the use of the public works, including streets and highways, when the substance of such regulations is indicated to the public by means of signs or signals; or (e) decisions issued in adjudicatory proceedings.”
We have intimated that “there is such a thing as an advisory or informational pronouncement by an administrative agency that may be issued lawfully in relation to a regulation (or a statute) without going through the procedures required for promulgation of a regulation.” Massachusetts Gen. Hosp. v. Rate Setting Comm’n, 371 Mass. 705, 706-707 (1977). It also may be true that “it is no use trying to frame an airtight definition of such pronouncements which would serve to distinguish them from regulations . . . .’’Id. at 707.