Defendant here is subject to a requirement, enacted after he committed the crimes of which he *800was convicted, that he register as a sex offender. I conclude, as does the lead opinion, that the sex offender registration requirement imposed on defendant is not a punishment and thus does not violate the United States Constitution’s prohibition against ex post facto laws. I do not join the lead opinion, however, because it misdescribes the United States Supreme Court’s current jurisprudence interpreting the ex post facto clause. I write separately to forestall the mischief this misdescription threatens to work in future cases.
I
The United States Constitution forbids states from enacting ex post facto laws—laws that impose punishment for conduct occurring before the law was enacted. (U.S. Const., art. I, § 10.) At issue in this case is whether the sex offender registration requirement imposed on defendant violates the ex post facto prohibition. Because the Legislature expanded the registration requirement to include the crimes committed by defendant only after he committed those crimes, it is not disputed that the requirement violates the ex post facto prohibition if it is a form of punishment.
The lead opinion concludes that the registration requirement is not punishment; in doing so, it cites to United States Supreme Court precedent interpreting the meaning of punishment under the Eighth Amendment of the United States Constitution, which prohibits cruel and unusual punishment and excessive fines. In addition, the lead opinion refuses to apply the multifactor test of punishment first articulated in Kennedy v. Mendoza-Martinez (1963) 372 U.S. 144 [83 S.Ct. 554, 9 L.Ed.2d 644] (hereafter the Mendoza-Martinez factors) and subsequently applied in numerous high court decisions. Although I, too, conclude that the registration requirement is not punishment, in my view the United States Supreme Court has laid out a different path of analysis for us to follow.
The United States Supreme Court has concluded that punishment has the same meaning for both ex post facto and double jeopardy purposes. In Kansas v. Hendricks (1997) 521 U.S. 346, 361 [117 S.Ct. 2072, 2081-2082, 138 L.Ed.2d 501], the high court applied a single test to determine that the involuntary civil commitment of a sex offender after the end of his criminal imprisonment was not punishment either for ex post facto or double jeopardy purposes.
The United States Supreme Court has also made clear that the concept of punishment has a meaning that varies in the context of different constitutional provisions. In particular, punishment has a different and broader meaning under the Eighth Amendment than it does for purposes of ex post *801facto, double jeopardy, and other constitutional provisions. In United States v. Ursery (1996) 518 U.S. 267, 286-287 [116 S.Ct. 2135, 2146-2147, 135 L.Ed.2d 549], the high court distinguished between the meaning of punishment under the double jeopardy clause of the Fifth Amendment and its different meaning under the excessive fines clause of the Eighth Amendment. In that decision, the high court held that civil forfeitures were not punishment for purposes of the Fifth Amendment double jeopardy clause even though they were punishment subject to scrutiny under the Eighth Amendment. (518 U.S. at pp. 286-287, 292 [116 S.Ct. at pp. 2146-2147, 2149].) The definition of punishment under the Eighth Amendment is a broad one, and encompasses some sanctions whose purpose is both remedial as well as punitive and some that are imposed in civil proceedings. (Austin v. United States (1993) 509 U.S. 602 [113 S.Ct. 2801, 125 L.Ed.2d 488].)
The lead opinion’s reliance in this ex post facto case on Eighth Amendment decisions such as Austin v. United States, supra, 509 U.S. 602, is thus misplaced. Instead, the proper test of punishment in this case is the one the high court has applied in double jeopardy and ex post facto cases.
The test of whether a government sanction is punishment for ex post facto and double jeopardy purposes has two parts. The first question is whether the legislature intended the sanction to be civil or criminal. “Whether a particular punishment is criminal or civil is, at least initially, a matter of statutory construction. [Citation.] A court must first ask whether the legislature, ‘in establishing the penalizing mechanism, indicated either expressly or impliedly a preference for one label or the other.’ ” (Hudson v. United States (1997) 522 U.S. 93, 99 [118 S.Ct. 488, 493, 139 L.Ed.2d 450].) The high court has viewed the civil or criminal character of the proceedings in which the sanction is imposed as a central and powerful indicium of legislative intent. (Kansas v. Hendricks, supra, 521 U.S. 346, 361 [117 S.Ct. 2072, 2081-2082] [“We must initially ascertain whether the legislature meant the statute to establish ‘civil’ proceedings.”]; accord, United States v. Ursery, supra, 518 U.S. 267, 288 [116 S.Ct. 2135, 2147] [“First, we ask whether Congress intended proceedings [for forfeiture]. . . to be criminal or civil.”]; United States v. One Assortment of 89 Firearms (1984) 465 U.S. 354, 362 [104 S.Ct. 1099, 1104-1105, 79 L.Ed.2d 361]; United States v. Ward (1980) 448 U.S. 242, 248 [100 S.Ct. 2636, 2641, 65 L.Ed.2d 742].)
If the legislature intended the sanction to be civil, then the second question is whether the sanction in purpose or effect is nonetheless so punitive that it can only be regarded as punishment. It is at this stage that the Mendoza-Martinez factors come into play. In the words of the high court:
“Even in those cases where the legislature ‘has indicated an intention to establish a civil penalty, we have inquired further whether the statutory *802scheme was so punitive either in purpose or effect,’ [citation] as to ‘transform] what was clearly intended as a civil remedy into a criminal penalty,’ [citation].
“In making this latter determination, the factors listed in Kennedy v. Mendoza-Martinez, 372 U.S. 144, 168-169 [83 S.Ct. 554, 567-568, 9 L.Ed.2d 644] (1963), provide useful guideposts, including: (1) ‘[w]hether the sanction involves an affirmative disability or restraint’; (2) ‘whether it has historically been regarded as a punishment’; (3) ‘whether it comes into play only on a finding of scienter’; (4) ‘whether its operation will promote the traditional aims of punishment—retribution and deterrence’; (5) ‘whether the behavior to which it applies is already a crime’; (6) ‘whether an alternative purpose to which it may rationally be connected is assignable for it’; and (7) ‘whether it appears excessive in relation to the alternative purpose assigned.’ It is important to note, however, that ‘these factors must be considered in relation to the statute on its face,’ [citation] and ‘only the clearest proof’ will suffice to override legislative intent and transform what has been denominated a civil remedy into a criminal penalty.” (Hudson v. United States, supra, 522 U.S. 93, 99-100 [118 S.Ct. 488, 493, 139 L.Ed.2d 450]; accord, Kansas v. Hendricks, supra, 521 U.S. 346, 361-362 [117 S.Ct. 2072, 2081-2082]; United States v. Ursery, supra, 518 U.S. 267, 288 [116 S.Ct. 2135, 2147] [“Second, we turn to consider whether the proceedings are so punitive in fact as to ‘persuade us that the forfeiture proceeding [s] may not legitimately be viewed as civil in nature,’ despite Congress’ intent.”], 291; United States v. One Assortment of 89 Firearms, supra, 465 U.S. 354, 362 [104 S.Ct. 1099, 1104-1105]; United States v. Ward, supra, 448 U.S. 242, 248 [100 S.Ct. 2636, 2641].)
Thus, the lead opinion errs when it concludes that the Mendoza-Martinez factors have no application in deciding under this second prong whether a putatively civil sanction is nonetheless punishment. (Lead opn., ante, at pp. 795-796, fn. 5; see Hudson v. United States, supra, 522 U.S. 93, 99-100 [118 S.Ct. 488, 493]; Kansas v. Hendricks, supra, 521 U.S. 346, 362 [117 S.Ct. 2072, 2082]; United States v. Ursery, supra, 518 U.S. 267, 291 [116 S.Ct. 2135, 2148-2149]; United States v. One Assortment of 89 Firearms, supra, 465 U.S. 354, 365 [104 S.Ct. 1099, 1106]; United States v. Ward, supra, 448 U.S. 242, 249-250 [100 S.Ct. 2636, 2641-2642].) The lead opinion’s assertion that the two-prong ex post facto punishment test can be applied without deciding whether the Mendoza-Martinez factors apply to ex post facto cases ignores that the Mendoza-Martinez factors are a central part of the second prong of that test.
n
Applying the United States Supreme Court’s two-part test of punishment to this case, the first question is whether our Legislature intended the *803proceedings in which the registration requirement is imposed to be criminal or civil. Here, the registration requirement was imposed in defendant’s criminal proceeding. Ordinarily, this would indicate that the Legislature intended the requirement to be a form of criminal punishment. It appears a novel question whether a sanction imposed in a criminal proceeding can nonetheless not be punishment; the United States Supreme Court’s case law on punishment has generally dealt with the converse question—when is a penalty imposed in a civil proceeding nonetheless punishment.
The purpose of the high court’s two-part test of punishment, however, seems to be to divine the true character of the sanction in question. Legislative intent is a powerful indication of the character of the sanction; if a legislature intended it as punishment it probably is punitive. And legislative intent as to the nature of the proceeding by which the sanction is to be imposed is ordinarily a strong proxy for legislative intent as to the character of the sanction itself. If the legislature intended the sanction to be imposed in a criminal proceeding it probably intended the sanction to be punitive. Probably, but not necessarily. In People v. McVickers (1992) 4 Cal.4th 81 [13 Cal.Rptr.2d 850, 840 P.2d 955], this court concluded that an AIDS testing requirement imposed in the course of the defendant’s criminal proceedings was not punishment for ex post facto purposes.
Here, likewise, it seems that our Legislature, having decided to extend registration at the discretion of the sentencing court to all sexually motivated crimes, made the registration determination part of the criminal proceeding not because it intended it to be an additional punishment for the crime but because, given that the determination turns on the facts of the underlying crime, it is far more efficient to make the determination as part of the criminal proceeding than in a separate civil proceeding (e.g., of the type used in Kansas v. Hendricks, supra, 521 U.S. 346, to civilly commit sex offenders at the end of their penal sentences).
I pass to the second prong of the test—whether the sanction is so punitive it can only be regarded as punishment. On balance, I conclude it is not. On the one hand, it is sophistic to assert as the People do that the registration is purely regulatory and not punitive. As the high court has explained, “the two primary objectives of criminal punishment” are “retribution” and “deterrence.” (Kansas v. Hendricks; supra, 521 U.S. 346, 361-362 [117 S.Ct. 2072, 2082].) We have said that one purpose of the registration requirement is “ ‘ “controlling crime and preventing recidivism” ’ ” (Wright v. Superior Court (1997) 15 Cal.4th 521, 527 [63 Cal.Rptr.2d 322, 936 P.2d 101]; see lead opn., ante, at p. 796)—in other words, deterrence. Part of this deterrence arises from the substantial lifetime burden that registration imposes on *804sex offenders. Further increasing that burden are the recently created provisions for public disclosure of the identity of most registered offenders (but not those who, like defendant, are subject to registration only by virtue of Penal Code section 290, subdivision (a)(2)(E)). When, as here, the “regulatory” purpose is deterrence and the deterrent effect arises from the burdens imposed on the offender, then “regulation” becomes indistinguishable from punishment.
On the other hand, a second purpose we have identified for the registration requirement, making sex offenders available for police surveillance (Wright v. Superior Court, supra, 15 Cal.4th 521, 527), seems more aimed at ferreting out crime after it has occurred than deterring its commission, and thus is not punitive. (Requiring automobile owners to register their vehicles aids in the detection of crime, but that does not make registration punitive.) Whatever punitive aspects the statute may have, they do not seem so overwhelming as to turn registration into a form of punishment. This is especially true in light of the high court’s conclusion in Kansas v. Hendricks, supra, 521 U.S. 346, 362 [117 S.Ct. 2072, 2082], that the civil commitment of sex offenders is not punishment. It is hard to imagine how requiring a sex offender to file an address report could be punishment when physically confining the same offender beyond the end of his criminal sentence is not.
Application of the Mendoza-Martinez factors listed above also supports the conclusion that registration is not punishment. (See Kennedy v. Mendoza-Martinez, supra, 372 U.S. 144, 168-169 [83 S.Ct. 554, 567-568].) Registration, although burdensome, does not seem to involve an affirmative disability or restraint, for it does not prevent the registrant from doing anything he could otherwise do. Government registration, at least in the abstract and considered apart from the shaming function of public disclosure, has not historically been regarded as a punishment.1 Registration does not solely promote retribution and deterrence, the traditional aims of punishment. There is an alternative purpose—police access to known sex offenders after a sex crime has been committed—to which the registration requirement may rationally be connected. Finally, the registration requirement does not appear excessive in relation to the alternative purpose. Two other factors weigh in *805the opposite direction—registration comes into play only on a finding of scienter, and the behavior to which it applies is already a crime—but these factors do not seem sufficient to turn registration into punishment.
Ill
As I have explained, the ex post facto test of punishment incorporates the Mendoza-Martinez factors and differs from the Eighth Amendment test of punishment. This understanding of the ex post facto punishment test makes clear why In re Reed (1983) 33 Cal.3d 914 [191 Cal.Rptr. 658, 663 P.2d 216], the decision the Court of Appeal relied upon to conclude that sex offender registration is punishment for ex post facto purposes, does not govern this case. At issue in Reed was the constitutionality of the sex offender registration requirement as applied to persons convicted of misdemeanor violations of Penal Code section 647, subdivision (a), a prohibition of lewd conduct in public places. This court in Reed applied the Mendoza-Martinez factors to conclude that registration is punishment for purposes of the prohibition against cruel or unusual punishment in article I, section 17 of the California Constitution, the state constitutional analogue of the Eighth Amendment. It further concluded that this punishment was cruel or unusual as applied to section 647, subdivision (a) misdemeanor offenders.
For the reasons stated above, I disagree with Reed’s conclusion that under the Mendoza-Martinez factors sex offender registration is punishment. This does not, however, mean that Reed was incorrect in holding that registration is punishment for purposes of article I, section 17 of the California Constitution. Given the holding in Austin v. United States, supra, 509 U.S. 602, that for Eighth Amendment purposes the concept of punishment is broader than the Mendoza-Martinez definition, it is possible for a sanction to be punishment under the Eighth Amendment or its state constitutional equivalent in article I, section 17 and yet not be punishment under the Mendoza-Martinez factors. Thus, my analysis does not call Reeds holding into question.2
Conclusion
Although I conclude, as does the lead opinion, that the registration requirement imposed on defendant is not punishment for ex post facto purposes, ! reach that result by the route set forth above. Most significantly, unlike the lead opinion I do not rely on the Eighth Amendment punishment *806case of Austin v. United States, supra, 509 U.S. 602, and I do rely on the factors set forth in Kennedy v. Mendoza-Martinez, supra, 372 U.S. 144. Finally, I agree that the case should be remanded to the Court of Appeal for it to consider in the first instance whether the trial court, in accordance with Penal Code section 290, subdivision (a)(2)(E), adequately stated its reasons for imposing the registration requirement.
Werdegar, J., and Brown, J., concurred.
Cases, unlike this one, in which defendant’s identity as a registered sex offender is open to widespread public disclosure would present significantly different issues in determining whether registration is punishment for either ex post facto or cruel and unusual punishment purposes. Public shaming of offenders has long been viewed as a form of punishment. (See generally, Whitman, What is Wrong With Inflicting Shame Sanctions? (1998) 107 Yale LJ. 1055; Kahan, What Do Alternative Sanctions Mean? (1996) 63 U. Chi. L.Rev. 591, 630-653; Massaro, Shame, Culture, and American Criminal Law (1991) 89 Mich. L.Rev. 1880, 1942-1943.) This case presents no occasion to decide whether public disclosure of a sex offender’s identity amounts to punishment for ex post facto purposes.
Although Penal Code section 647, subdivision (a), the crime at issue in Reed, is no longer an automatically registrable offense under Penal Code section 290, it continues to be registrable at the discretion of the sentencing court under the catchall provision of section 290, subdivision (a)(2)(E).