(concurring, with whom Abrams and Marshall, JJ., join). I join in the opinion of the court. The statute as applied to the plaintiff certainly has the defects identified in the court’s opinion and they are sufficient to justify the relief we grant today. Because the statute goes beyond what the Justices indicated was constitutionally permissible in the Opinion of the Justices requested by the Senate in respect to a more carefully calibrated statute, see Opinion of the Justices, 423 Mass. 1201 (1996), and goes beyond the statutes enacted in New York and New Jersey and found constitutional by State and Federal courts, *147see Doe v. Pataki, 120 F.3d 1263, 1265-1266 (2d Cir. 1997); E.B. v. Verniero, 119 F.3d 1077 (3d Cir. 1997); Doe v. Poritz, 142 N.J. 1, 15-17 (1995), I believe it important to restate some fundamental principles that apply to legislation of this sort.
I
The plaintiff complains that the statute, as applied to him, violates both State and Federal procedural due process rights. He also claims that as applied to him the act violates State and Federal guarantees against the ex post facto imposition of punishment, double jeopardy and cruel and unusual punishment. In the Opinion of the Justices, the Justices considered, in a narrower context, these several rights, and noted that quite apart from the particular analyses each of them requires, they have a systematic relation among them which controls and organizes these particular analyses. See Opinion of the Justices, supra at 1218-1219. The many detailed protections for the criminal process set out in the Federal and State Constitutions necessarily presuppose that due process for the purposes of imposing criminal sanctions has a particular meaning distinct from what due process may mean in other contexts. That distinct body of rules may not be allowed to be elided into the general due process analysis of reasonableness as explicated in Mathews v. Eldridge, 424 U.S. 319 (1976). Marking off this distinct domain is the concept of punishment. See, e.g., United States v. Ursery, 518 U.S. 267 (1996); Montana v. Kurth Ranch, 511 U.S. 767, 777 (1994); United States v. Ward, 448 U.S. 242, 248 (1980). But punishment is not measured simply by the severity of the imposition — as there are minor criminal sanctions and major regulatory burdens — but by the kind of imposition. Condemnation and a judgment of guilt are the hallmarks of the criminal law. Punishment is visited on those who knowingly transgress norms and limits imposed by law. Regulation simply aims at procuring conformity with those limits, whatever the state of mind of the actor may be in respect to them. But to keep the concept of regulation in its place, it may be said that, while activities, professions, or relationships may be regulated, we do not have a general regime regulating adult competent persons as such. See Opinion of the Justices, supra at 1223. Persons are left to choose freely and if they make the wrong choices they are subject to retrospective condemnation and punishment. This is not merely a conceptual difference. It is a profound expres*148sion of our Constitution’s conception of human nature and of the relation of individuals to the State. Although these generalities do not determine the answer to particular cases, they set the principles which guide the doctrines that do.
In working out these constitutional principles the law has been practical and flexible, but not to the point where the principles disappear or become meaningless. We have considered and allowed regulations of persons in two kinds of contexts. First, we have said that the prospective regulatory burden (as opposed to the criminal sanctions) may be imposed where it is ancillary, or preliminary, to the regular working of the criminal process and is exhausted when that process reaches its conclusion. That is how we have conceived the justification for preventative detention: as a kind of preliminary relief for the government where there is real and grave danger to the public prior to the conclusion of the criminal process, which still remains “the main event.” See Mendonza v. Commonwealth, 423 Mass. 771, 781 (1996). Second, even where the criminal process has run its course (or may never even be invoked), additional or alternative, perhaps quite stringent, regulatory measures may be permissible where the danger is great and the measures are carefully calibrated to the needs of the particular case. Thus in Kansas v. Hendricks, 117 S. Ct. 2072 (1997), the Supreme Court upheld a Kansas statute providing for involuntary civil commitment of criminals after their scheduled release from serving their criminal punishment, so long as they were judicially determined to be dangerous sexual predators suffering from a “mental abnormality” and the State provided a variety of procedural safeguards both prior and subsequent to the judicial determination. Id. at 2077, 2086. This is the extreme case where a total deprivation of liberty, which began as punishment, continues as a regulatory measure. But the degree and specificity of the threat in that case was extreme also. The notification and registration provisions in this statute fall into the second category and, because they follow on and are closely associated with criminal condemnation, raise in an urgent way the constitutional imperative that the distinctiveness of punishment and the stringently limited regime surrounding its imposition not be elided under a loose and casual invocation of the concept of regulation.
Although the distinction between punishment and regulation is practical and not rigid there are a number of considerations *149that bear on how that distinction must be made to preserve the integrity of fundamental constitutional principles. We have recognized in a number of contexts, see Luk v. Commonwealth, 421 Mass. 415, 427-428 (1995), and cases cited, that regulation may be imposed after a careful weighing of three factors: the kind and severity of the regulatory imposition, the kind and severity of the danger sought to be averted, and the aptness of the fit between the remedial measure and the danger to be averted. See Opinion of the Justices, supra at 1224-1225. I discuss each of these in turn as they bear on this statute.
II
The Opinion of the Justices contains a sufficient consideration of the burdens of some forms of community notification that they need not be rehearsed here. See Opinion of the Justices, supra at 1226. It should be noted, however, that this statute goes beyond the forms of notification to which the Justices were asked to respond, to provide for notification to any member of the public who inquires with the police, and, for the more serious levels of classification, very broad dissemination to community organizations and public posting of notices on cable television and in newspapers. See G. L. c. 6, §§ 178I, 178J, 178K (2) (a), 178K (2) (c); 803 Code Mass. Regs. § 1.03(5), (6) (1996). These are some of the several ways in which the present statute moves beyond a carefully calibrated approach to one of undifferentiated generality.
What is before us now, but was not before the Justices, is the registration requirement. Although community notification is a more novel regulatory measure and one with obviously harsh consequences, registration presents a different and importantly distinct kind of constitutional danger. Notification, after all, relates to the authorities’ own dissemination of information properly within their possession. Cf. Paul v. Davis, 424 U.S. 693 (1976). There are independent values served in giving the public access to what the government knows, and notification may entail no more than reorganizing and collating that material in a form that makes it more accessible and more responsive to the public’s desire to know it. Registration, on the other hand, forces an action on the person required to register. It is a continuing, intrusive, and humiliating regulation of the person himself. To require registration of persons not in connection with any particular activity asserts a relationship between *150government and the individual that is in principle quite alien to our traditions, a relationship which when generalized has been the hallmark of totalitarian government. This is not to say that registration is always an unjustifiable infringement on liberty, but only that any justification for it must take into account its peculiar burdens in measuring them against the harm to be averted.
Next I come to the justifying danger. The Opinion of the Justices recounts the large amount of data offered, particularly by the United States as amicus curiae, to show the high rates of recidivism, especially by sex offenders who prey on children. That data figured prominently in the Justices’s analysis, Opinion of the Justices, 423 Mass, at 1227-1228, as it has in tire principal opinions upholding narrower statutes in other jurisdictions. See Doe v. Pataki, 120 F.3d 1263, 1265-1266 (2d Cir. 1997); Doe v. Poritz, 142 N.J. 1, 15-17 (1995). The Commonwealth presents no such data today, but instead relies simply on the legislative judgment in passing the statute in this form. Where government must show an interest of more than the usual degree of urgency to justify imposition on the individual, the simple invocation of its legislative judgment, buttressed perhaps by a showing of a rational basis for that judgment, will not do. Otherwise the constitutional restraints the State is asked to overcome would be rendered empty. In this case the urgency must be shown by the severity of the harm and the likelihood of its occurrence. There may be offenses (e.g., rape of a child) such that a general legislative category, without further particularization to the individual case, will be sufficient to make out the requisite justification. The omnibus, catch-all nature of some of the offenses included in this statute are at a far remove from such a showing. The plaintiff’s offense in this case, for all we are told, portends no danger beyond embarrassment. And that is not enough. Although the touching here may well have been technically assaultive as not consented to, the circumstances make clear that it took place at a place and in a context where the plaintiff had every reason to believe that those he met were seeking just the kind of encounter he initiated. This is not to say that, if the government could show that one engaging in behavior that itself does not implicate the kind of danger that the statute seeks to guard against is also likely to engage in substantially more harmful conduct or direct his attention toward children, a predicate for registration and some form of notification might not be laid. We *151have been offered nothing of that sort. That is the focus of the court’s opinion and it is a judgment that I believe is entirely correct. Standing between the cases where statutorily defined harm itself may be shown to pose a sufficient danger in a categorical way, and those cases where only a particularized showing will do, may be cases where the statutorily defined predicate is sufficient to justify the regulation, but only if the subject of the regulation has the opportunity to show that he should be exempted from some or all of its strictures. The legislation in some States has such provisions. See, e.g., Doe v. Poritz, supra at 106-108; N.Y. Correct. Law § 168-o (McKinney Supp. 1997); Wash. Rev. Code § 9A.44.140(2) (1994).
The final element in the constitutional balance is aptness of fit. It is not enough that the regulation be directed at a serious harm; there must be an adequate showing as well that the particular regulatory measures are well-adapted to minimizing that danger. Registration and notification in respect to offenses especially likely to victimize vulnerable populations are thought to have a particular aptness as they allow those who care for such populations to take proper precautions for their protection, because ordinary prudence will not be enough. Of course some harms are so great that no special victim vulnerability need be shown. But once again, this case is as far as can be imagined from such an example.
III
Registration and notification may be useful, and in any event are constitutionally permissible means for protecting the public, but only if they are narrowly tailored to a grave danger. Indiscriminate extensions such as appear in this case will only provoke continuous and often successful litigation. This will burden the courts and the relevant administrative agency to such a point that the purposes of the scheme will be delayed and perhaps defeated even in the carefully limited class of cases to which it properly applies.