Thе plaintiff, Patrick J. Haran, is a physician licensed to practice medicine in the Commonwealth and in the State of New York. In 1979, Haran was found by the disciplinary authority in New York to have been guilty of negligence and professional incompetence on at least twelve occasions. His license to practice in New York was revoked. Nearly one year later, the Massachusetts Board of Registration in Medicine (board) promulgated a regulation permitting it, in disciplinary hearings, to give collateral estoppel effect to a sister State’s disciplinary actions “for reasons substantially the same” as those for which physicians may be disciplined in the Commonwealth. See 243 Code Mass. Regs. § 1.03 (5) (a) (12) (1980) (hereafter, par. 12). 1
*573 In 1981, the board initiated action against Harаn, relying on the New York suspension. In 1982, Haran was reinstated in New York on the sole ground that he had “demonstrated his rehabilitation.” Hearings then proceeded in Massachusetts on the 1981 complaint. The hearing officer for the board, relying on par. 12, ruled that the New York finding of negli *574 gence precluded Haran from relitigating the question whether he had violated Massachusetts disciplinary standards; therefore, the hearings were limited to the issue of what sanctions to impose. In 1984, the board accepted the hearing officer’s findings and recommendations and voted to suspend Haran’s Massachusetts license for two years. The board, however, taking cognizance of the later New York finding that Haran had rehabilitated himself, stayed the suspension. Haran appealed to a single justicе of this court pursuant to G. L. c. 112, § 64 (1984 ed.). The single justice vacated the suspension, ruling that the board had applied par. 12 improperly because (1) it was applied retroactively, and (2) regulations promulgated pursuant to G. L. c. 30A (1984 ed.) cannot be given retroactive effect. The board appealed. We reverse and reinstate the decision of the board.
We need not reаch the question whether regulations promulgated by the board pursuant to G. L. c. 30A can be given retroactive effect. Rather, we hold that the board did not apply par. 12 retroactively. As we have stated with respect to statutes, a regulation is not held to have been applied retroactively merely because “it draws on antecedent facts for its operation.” McCarthy v. Sheriff of Suffolk County, 366 Mass. 779, 781 (1975). “It is оnly where vested substantive rights of the parties have been adversely affected that we can say a statute operates retroactively.” Id.
Haran has not demonstrated that his vested substantive rights were affected by the board’s reliance on par. 12. The regulation does not alter a physician’s substantive rights by extending in any way the range of conduct for which a physician may be disciplined in Massachusetts. Rather, par. 12 permits discipline of a physician on the basis of foreign actions only where the foreign grounds of decision are “substantially the same” as the grounds for local discipline set out at 243 Code Mass. Regs. § 1.03 (5) (a) (l)-(ll) (1980).
Haran argues that the presence in par. 12 of the modifier “substantially” leaves the regulation so loosely drafted as to permit the board to discipline physicians for conduct proscribed elsewhere, but not in the Commonwealth. A contrary view of *575 the word “substantially” seems more reasonably to be the intention of the board. The board’s use of the principle of collateral estoppel in situations in which there is no significant difference between a sister State’s “reasons” for discipline and the grounds that are cognizable in the Cоmmonwealth is clearly proper, as even Haran concedes, to prevent physicians from relitigating questions decided against them in other States. This purpose would fail if the board’s regulations had to be so drafted as to account for mere variations in verbal form and not in substantive content in the several States. The use of the adverb “substantially” limits, rather than enlarges, the disciplinary powers of the board to situations in which there is no substantive difference between foreign and local grounds for discipline.
The regulation, as applied to Haran, did not permit the board to use the New York findings to penalize him for conduct not otherwise actionable in Massachusetts. There is no meaningful difference between the “negligence ... on more than one occаsion” of which Haran was found guilty in New York and the requirement of a showing in Massachusetts of “negligence on repeated occasions.” 2
Haran argues that the board’s application of par. 12 deprived him of an alleged right to rely on a settled expectation that he would enjoy a “full opportunity” in Massachusetts “to disprove” what was proved in New York. In essence, he asserts a vested substantive right to a second bite at the adjudicative apple. No such right exists. This court has authorized an expanded use of the doctrine of collateral estoppel, in part because we recognize “the strong and oft-stated public policy of limiting each litigant to one opportunity to try his case on the merits.”
Home Owners Fed. Sav. & Loan Ass’n
v.
Northwestern Fire & Marine Ins. Co.,
Apart from the issue of retroactivity, Haran maintains that the board violated his right to due process by giving overbroad collateral estoppel effect to the findings of the New York authorities. Wе disagree. The board’s authority to discipline physicians derives from the principle, long recognized in this Commonwealth, that “[t]he right of a physician to toil in his profession . . . with all its sanctity and safeguards is not absolute. It must yield to the paramount right of government to protect the public health by any rational means.”
Lawrence
v.
Board of Registration in Medicine,
The due process arguments raised by Haran stem from rulings made by the board’s hearing officer. Early in the Massachusetts *577 hearings, the hearing officer denied Haran’s motion for a “directed verdict” of dismissal. The board’s complaint counsel had introduced only the following evidence: Haran’s Massachusetts registration; the Massachusetts disciplinary regulations, 243 Code Mass. Regs. § 1.03 (5) (a) (1)-(12) (1980); and records relevant to the New York proceedings against Haran. These last included findings of that State’s hearing committee, which in turn included a conclusion that Haran was guilty of “negligence and incompetence on more than one occasion” and separate factual findings of negligence and incompetence on twelve separate occasions. Implicit in the hearing officer’s denial of Haran’s motion for a “directed verdict” was a ruling that this evidence was sufficient to support a decision by the board to discipline Haran on the basis that New York’s revocation of Harаn’s license established his liability in Massachusetts for discipline.
Haran maintains first that the hearing officer’s rulings resulted in a purely mechanical application of the New York findings, which effectively denied him a hearing because he was not allowed to confront “the
sole
‘witness’ against him (the New York revocation order)” (emphasis in original). Apparently, Haran argues that the board’s use of collаteral estoppel offensively pursuant to par. 12 denied him a hearing on the issue of his liability to discipline, which was otherwise guaranteed him by G. L. c. 112, §§ 5 and 61, and G. L. c. 30A, § 10. “In appropriate circumstances, however, the offensive use of collateral estoppel is a generally accepted practice in American courts.”
Aetna Casualty & Sur. Co.
v.
Niziolek, supra
at 744. When determining whether the offensive use of collateral estoppel has afforded a defendant due process, “[f]airness is the decisive consideration.”
Id.
at 745. See
Parklane Hosiery Co.
v.
Shore,
Still, the touchstone of our analysis is fairness in all the circumstances. Haran maintains that it is fundamentally unfair to permit the board to treat New York’s revocation of his license as preclusive of litigation without also giving collateral estoppel effect to that State’s subsequent determination of what he terms his “present qualification for licensure.” The supposed asymmetry is only superficial. Findings of negligence and findings of rehabilitation are both, in a technical sense, “findings *579 of fact,” but there the similarity ends. A finding of nеgligence provides an answer to a narrow factual question — whether, in a particular instance or set of instances, a physician’s performance fell below the standard required by law. In contrast, reinstatement of a physician’s registration in this Commonwealth, by proof of rehabilitation or otherwise, “will be granted only if the Board determines that doing so would advance the public interest.” 243 Code Mass. Regs. § 1.05 (6) (c) (1979). Thus, a finding of rehabilitation and reinstatement requires weighing and balancing a wide range of considerations peculiar to the petitioner in light of the public interest. The former kind of question — whether negligence occurred — is well suited to resolution by collateral estoppel; the latter kind of question is not. By the promulgation of par. 12 in 1980, the board’s regulations have trеated these two kinds of questions differently, authorizing the use of issue preclusion as to one and not the other.
We cannot say that this regulatory design is unreasonable or unfair. “One of the purposes which lead to the creation of such boards is to have decisions based on evidential facts under the particular statute made by experienced officials with an adequate aрpreciation of the complexities of the subject which is entrusted to their administration.”
Arthurs
v.
Board of Registration in Medicine,
Haran also maintains that the board, by the hearing officer’s rulings, prevented him from presenting evidence on alleged dissimilarities between the New York and Massachusetts disciplinary standards; he insists that the board should have re *580 quired its complaint сounsel to demonstrate, by reference to the comparative case law of New York and Massachusetts, that the “negligence” for which he lost his license in New York is legally indistinguishable from the “negligence” that is proscribed in Massachusetts by G. L. c. 112, § 5 (c). The argument is somewhat disingenuous. The question of the similarity of legal standards is not one of evidence and fact, but one of law. The hearing оfficer could take administrative notice of the pertinent New York law. See G. L. c. 30A, § 11 (5); G. L. c. 233, § 70 (1984 ed.). We need not be detained longer by this argument, as we have answered it in the earlier portion of this opinion. 6
The board, in accepting the recommendations of the hearing officer on the substantial similarity of the New York and Massachusetts standards, properly fulfilled, under G. L. c. 112, §5, its “role ... in the over-аll statutory scheme [which] is to take primary responsibility in the regulation of the practice of medicine in the Commonwealth ‘in order to promote the public health, welfare, and safety.’ ”
Levy
v.
Board of Registration & Discipline in Medicine,
Finally, Haran maintains that the board violated his right to due process when it gave collateral estoppel effect to the findings of negligence by the New York authorities without considering whether he had had a full and fair opportunity to litigate that question in the New York proceedings. Admittedly, “[r]edetermination of issues is warranted if there is reason to doubt the quality, extensiveness, or fairness of procedures followed in the prior litigation.”
Montana
v.
United States,
The order of the single justice is vacated. Hie case is remanded to the county court for entry of judgment reinstating and affirming the decision of the board.
So ordered.
Notes
The authority of the board to discipline physicians is found in G. L. c. 112, §§ 5 and 61 (1984 ed.). Section 5 provides in relevant part:
*573 “The board shall investigate all complaints relating to the proper practice of medicine by any person holding a certificate of registration ....
“The board may, after a hearing pursuant to chapter thirty A, revoke, suspend, or cancel the certificate of registration, or reprimand, censure, impose a fine ... or otherwise discipline a physician . . . upon proof satisfactory to a majority of the board that said physician: —
«
“(с) is guilty of gross misconduct in the practice of medicine or of practicing medicine fraudulently, or beyond its authorized scope, or with gross incompetence, or with gross negligence on a particular occasion or negligence on repeated occasions;
“(h) is guilty of violating any rule or regulation of the board, governing the practice of medicine.
“The boаrd shall, after proper notice and hearing, adopt rules and regulations governing the practice of medicine in order to promote the public health, welfare, and safety and nothing in this section shall be construed to limit this general power of the board.”
See
Raymond
v.
Board of Registration in Medicine,
The regulation in issue, 243 Code Mass. Regs. § 1.03 (5) (a) (1980), provides in part:
“A complaint against a physician must allege that a registrant is prаcticing medicine in violation of law, regulations, or good and accepted medical practice and may be founded on any of the following:
6Í
“3. gross misconduct in the practice of medicine, or practicing medicine fraudulently, or beyond its authorized scope, or with gross incompetence, or with gross negligence on a particular occasion or negligenсe on repeated occasions;
“11. violation of any rule or regulation of the Board governing the practice of medicine.
“12. having had his right to practice medicine in another jurisdiction restricted in any way as a result of a disciplinary action by the proper licensing authority for reasons substantially the same as those set forth in243 CMR 1 .03 (5) (a) (I) through (11).”
Compare the definition of professional misconduct in New York Educ. Law § 6509(2) (McKinney 1985), which, in part, defines professional misconduct as “[p]racticing the profession . . . with . . . negligence or incompetence on more than one occasion,” with 243 Code Mass. Regs. § 1.03 (5) (a) (3) (1980), requiring the proof of “negligence on repeated occasions. ” The findings in New York of twelve occasions of negligence clearly suffice under both standards.
Thus, we need not reach the question whether, if c. 30A does permit retroactive application, such application of par. 12 would violate the canons of due process.
On the facts of this case, we are not presented with a situation in which the board applied par. 12 after the initially-revoking sister State had reinstated the physician on grounds which called into question the validity of its revocation of his license in the first instance. In those circumstances, the application of par. 12 would be “inconsistent with... previous judgments in favor of the defendant.” Parklane Hosiery Co., supra at 330. The sole ground for Haran’s reinstatement in New York was the finding that he had “adequately demonstrated his rehabilitation.” There is no inconsistency. Indeed, because New York’s second judgment in Haran’s case was based on the assumption that rehabilitation was required prior to reinstatement, this second judgment implicitly affirmed the original findings of negligence.
Haran argues that he might have obtained a different result in Massachusetts had not the hearing officer’s rulings foreclosed the possibility of introducing the expert testimony of Dr. James Rhea, a professor of radiology. It does not appear from the rеcord that this evidence was offered at, or excluded from, the initial New York proceedings. We would be indulging in pure speculation if we were to conclude that Haran might have enjoyed outcome-determinative evidentiary procedures in Massachusetts which were not available to him in New York.
Haran also protests that, due to what he sees as a lack of evidencе in the form of interpretive case law, the hearing officer’s granting of the complaint counsel’s motion for partial summary decision was erroneous as matter of law and should be set aside pursuant to G. L. c. 30A, § 14 (7) (e), because that ruling is totally unsupported by substantial evidence. This claim, too, is obviated by our ruling that the hearing officer was correct in finding substantial similarity from a facial reading of the New York documents and record introduced by the complaint counsel.
Haran seeks to attack the fairness of the New York proceedings, detailing various grounds. None of these issues is briefed adequately. Haran’s reference to the memorandum submitted to the single justice does not comply with the requirement of Mass. R. A. P. 16 (a) (4), as amended,