Opinion
GEORGE, C. J.Following defendant Luis Castellanos’s conviction of a series of criminal offenses, the trial court ordered him to register as a sex offender pursuant to a provision in Penal Code section 290 that became effective after defendant committed those offenses. The Court of Appeal struck the trial court’s order, concluding that requiring defendant to register as a sex offender violates the ex post facto clauses of the federal and California Constitutions (U.S. Const., art. I, § 10; Cal. Const., art. I, § 9). We disagree. As explained below, the trial court’s order is valid because the requirement that a person register as a sex offender does not constitute punishment for purposes of ex post facto analysis.
I
In April 1994, defendant introduced himself to a member of the women’s basketball team at Glendale College and subsequently appeared at her house. She allowed defendant to enter the residence but said she was getting ready to leave (which was not true) and left him in the living room for “a minute or two” while she went upstairs to get her keys. Then both she and defendant left the house. The student went to her automobile and defendant appeared to go to his. She drove around the block, parked, and walked back to her house “through the back way” in order to avoid defendant if he still was present. As she approached her house, she saw defendant inside, replacing a screen on a window. She went to her grandmother’s house and called the police.
The police arrested defendant the following day while he was attending a class at Glendale College. Defendant was carrying twenty-six $100 bills. In his locker, he had a three-month-old sports section of a local newspaper that contained an article that mentioned the student. In his backpack, police found a set of keys that belonged to a teacher at Glendale College, an address book, and a list of names of 14- and 15-year-old girls.
Defendant made a detailed confession. He explained that he had determined where the student lived by peering over her shoulder as she filled out *789a form at the library, and had memorized her address. While he was inside her residence and she was upstairs retrieving her keys, he unlocked a window and opened it a few inches. He left the house and pretended to go to his automobile, but when the student was out of sight he returned to her residence and climbed in through the window he had opened. After entering her bedroom, he stole a pair of her panties “as a memento of his contact” with her.
Defendant admitted that this was not his first burglary and that he had burglarized the homes of many of the girls named on the list found in his backpack. Each time, he took a pair of the girl’s panties. Often, he also took money and photographs of the girl. He consented to have the police search the premises where he lived with his mother. At defendant’s direction, the police looked inside a crawl space above the closet in defendant’s bedroom and found, buried in the insulation, a trashbag that contained 27 pairs of women’s panties, numerous photographs of teenage girls, and some pubic hairs in plastic bags with notes identifying their sources.
The police contacted the girls involved. Many had not known that their property had been taken, but identified their underwear and photographs. Others had noticed that money was missing, usually in amounts close to $100, but had not suspected a burglary had occurred. On one occasion, $2,720 had been taken.
Defendant was convicted of 13 counts of first degree burglary in violation of Penal Code section 4591 and 3 counts of receiving stolen property in violation of section 496, subdivision (a). He was sentenced to a term of 14 years in prison and ordered to register as a sex offender, pursuant to section 290, upon his release from custody.
Defendant argued on appeal that requiring him to register as a sex offender violates the ex post facto clauses of the federal and California Constitutions, because the provision in section 290 that requires him to register took effect after he committed the offenses of which he was convicted. The Court of Appeal agreed and modified the judgment of conviction by striking the order requiring defendant to register as a sex offender, stating it was bound by this court’s decision in In re Reed (1983) 33 Cal.3d 914 [191 Cal.Rptr. 658, 663 P.2d 216].
II
At the time defendant committed the present offenses in 1993 and 1994, section 290 required a person convicted of an enumerated sex-related crime *790to register as a sex offender. The registration requirement is lifelong, and includes furnishing to the chief of police of the city in which the offender resides (or to the sheriff of the county, if the offender resides in an unincorporated area) a written statement, fingerprints, and a photograph, which are forwarded to the California Department of Justice. Failure to register is a criminal offense. “The purpose of section 290 is ‘to assure that persons convicted of the crimes enumerated therein shall be readily available for police surveillance at all times because the Legislature deemed them likely to commit similar offenses in the future.’ [Citations.]” (In re Reed, supra, 33 Cal.3d 914, 919.) The crimes enumerated in former section 290 included rape, sodomy, and oral copulation, but did not include the crimes of burglary and receiving stolen property committed by defendant.
On January 1, 1995 (after defendant committed the present offenses, but before he was convicted), an amendment to section 290 took effect that, among other changes, added subdivision (a)(2)(E), which broadened the scope of the statute by requiring registration upon conviction of “any offense ... if the court finds at the time of conviction that the person committed the offense as a result of sexual compulsion or for purposes of sexual gratification.”2 The trial court ordered defendant to register as a sex offender pursuant to this provision. As noted above, the Court of Appeal struck the trial court’s order, holding that it violated the ex post facto clauses of the federal and state Constitutions.
Article I, section 10, clause 1 of the federal Constitution states in pertinent part: “No state shall . . . pass any ... ex post facto law . . . .” Article I, section 9 of the California Constitution similarly states that an “ex post facto law . . . may not be passed.” The California provision is analyzed in the same manner as its federal counterpart. (People v. Grant (1999) 20 Cal.4th 150, 158 [83 Cal.Rptr.2d 295, 973 P.2d 72]; People v. McVickers (1992) 4 Cal.4th 81, 86 [13 Cal.Rptr.2d 850, 840 P.2d 955]; Tapia v. Superior Court (1991) 53 Cal.3d 282, 295-296 [279 Cal.Rptr. 592, 807 P.2d 434].)
'More than 200 years ago, in Calder v. Bull (1798) 3 U.S. (3 Dall.) 386, 390 [1 L.Ed. 648, 650], the United States Supreme Court discussed the *791meaning of the federal ex post facto clause: “The prohibition, in the letter, is not to pass any law concerning, and after the fact; but the plain and obvious meaning and intention of the prohibition is this; that the Legislatures of the several states, shall not pass laws, after a fact done by a subject, or citizen, which shall have relation to such fact, and shall punish him for having done it.” The court then listed the type of laws that were ex post facto laws: “1st. Every law that makes an action, done before the passing of the law, and which was innocent when done, criminal; and punishes such action. 2nd. Every law that aggravates a crime, or makes it greater than it was, when committed. 3rd. Every law that changes the punishment, and inflicts a greater punishment, than the law annexed to the crime, when committed. . . .” (Ibid.)
In Collins v. Youngblood (1990) 497 U.S. 37, 41 [110 S.Ct. 2715, 2718, 111 L.Ed.2d 30], the high court reaffirmed this interpretation of the ex post facto clause: “Although the Latin phrase ‘ex post facto’ literally encompasses any law passed ‘after the fact,’ it has long been recognized by this Court that the constitutional prohibition on ex post facto laws applies only to penal statutes which disadvantage the offender affected by them.” Relying upon the decision in Calder v. Bull, supra, 3 U.S. (3 Dall.) 386, the high court restated the prohibition of the ex post facto clause in simple terms: “Legislatures may not retroactively alter the definition of crime or increase the punishment for criminal acts.” (Collins v. Youngblood, supra, 497 U.S. 37, 43 [110 S.Ct. 2715, 2719].)
In the present case, the amendment to section 290 that took effect after defendant committed the charged offenses did not alter the definition of the crimes of which defendant was convicted, but it did require defendant to register as a sex offender. Accordingly, application of this amendment to defendant would violate the ex post facto clauses of the federal and state Constitutions only if the sex offender registration requirement constitutes an increase in the punishment for defendant’s criminal acts.3
In People v. McVickers, supra, 4 Cal.4th 81, we held that requiring a defendant convicted of certain sex offenses to provide a blood sample for AIDS testing did not constitute punishment for purposes of ex post facto analysis. We observed that “the ex post facto clause prohibits not just a burden but a more burdensome punishment.” (Id. at p. 84, italics in original.) *792Noting that the decision in Collins v. Youngblood, supra, 497 U.S. 37, “furnishes no definitive answer to the question of the meaning of punishment” (People v. McVickers, supra, 4 Cal.4th 81, 85), we turned for guidance to earlier federal cases, including the decision in Kennedy v. Mendoza-Martinez (1963) 372 U.S. 144 [83 S.Ct. 554, 9 L.Ed.2d 644], and concluded that requiring a defendant to provide a blood sample for AIDS testing may be a burden, but it does not constitute punishment for purposes of ex post facto analysis, because neither the purpose nor the effect of the provision is punitive. To the contrary, the AIDS testing provision “has a legitimate nonpunitive governmental purpose.” (People v. McVickers, supra, 4 Cal.4th 81, 89.)
In so holding, we twice cited the decision of the Arizona Supreme Court in State v. Noble (1992) 171 Ariz. 171 [829 P.2d 1217] that “held that a statute requiring registration of sex offenders did not violate the ban on ex post facto legislation as applied to a defendant whose crimes preceded its enactment because the overriding purpose of the statute was ‘facilitating the location of child sex offenders by law enforcement personnel,’ a purpose unrelated to punishment. [Citation.]” (People v. McVickers, supra, 4 Cal.4th 81, 87, 89.)
The Arizona Supreme Court is not alone in concluding that a sex offender registration requirement does not constitute punishment for purposes of ex post facto analysis. As recognized by the Court of Appeal in People v. Fioretti (1997) 54 Cal.App.4th 1209, 1214 [63 Cal.Rptr.2d 367], “[Virtually every court recently considering sex offender registration laws has held that these requirements are regulatory rather than punitive. (See, e.g., Kitze v. Com. (1996) 23 Va.App. 213 [475 S.E.2d 830]; Opinion of the Justices to the Senate (1996) 423 Mass. 1201 [668 N.E.2d 738]; State v. Myers (1996) 260 Kan. 669 [923 P.2d 1024]; Artway v. Attorney General of State of N.J. (3d Cir. 1996) 81 F.3d 1235, 1267; State v. Noble (1992) 171 Ariz. 171 [829 P.2d 1217, 1219-1220]; State v. Ward (1994) 123 Wn.2d 488 [869 P.2d 1062].)” (See also Doe v. Pataki (2d Cir. 1997) 120 F.3d 1263; State v. Burr (N.D. 1999) 598 N.W.2d 147; State v. Pickens (Iowa 1997) 558 N.W.2d 396; Doe v. Poritz (1995) 142 N.J. 1 [662 A.2d 367, 36 A.L.R.5th 711]; State v. Costello (1994) 138 N.H. 587 [643 A.2d 531]; State v. Manning (Minn.Ct.App. 1995) 532 N.W.2d 244.)
Six months after our decision in McVickers, the United States Supreme Court decided Austin v. United States (1993) 509 U.S. 602 [113 S.Ct. 2801, 125 L.Ed.2d 488]. The issue in the Austin case was whether a civil forfeiture under 21 United States Code section 881(a)(4) and (7) of property used to facilitate the transportation or possession of controlled substances (in *793that case a mobilehome and an automobile repair shop) constituted an excessive fine prohibited by the Eighth Amendment of the United States Constitution. The question turned on whether the forfeiture constituted punishment: “The Excessive Fines Clause limits the government’s power to extract payments, whether in cash or in kind, ‘as punishment for some offense.’ [Citation.] ‘The notion of punishment, as we commonly understand it, cuts across the division between the civil and the criminal law.’ [Citation.] ‘It is commonly understood that civil proceedings may advance punitive as well as remedial goals, and, conversely, that both punitive and remedial goals may be served by criminal penalties.’ [Citations.] Thus, the question is . . . whether [the forfeiture] is punishment.” (Austin v. United States, supra, 509 U.S. 602, 609-610 [113 S.Ct. 2801, 2805-2806], fn. omitted, italics in original.)4
Reviewing the history of forfeiture provisions in both England and the United States, the court in Austin concluded “that forfeiture generally and statutory in rem forfeiture in particular historically have been understood, at least in part, as punishment.” (Austin v. United States, supra, 509 U.S. 602, 618 [113 S.Ct. 2801, 2810], fn. omitted.) The court then examined the federal statutes at issue and found “nothing in these provisions or their legislative history to contradict the historical understanding of forfeiture as punishment.” (Id. at p. 619 [113 S.Ct. at p. 2810].) Having determined that forfeiture constituted punishment within the meaning of the excessive fines clause of the Eighth Amendment, the court remanded the matter to the lower court for a determination of whether the forfeiture or fine in that case was “excessive.” (509 U.S. at pp. 622-623 [113 S.Ct. at p. 2812].)
In United States v. Ursery (1996) 518 U.S. 267 [116 S.Ct. 2135, 135 L.Ed.2d 549], the United States Supreme Court adopted a different approach to determining what constitutes punishment, holding that the double jeopardy clause of the Fifth Amendment of the United States Constitution did not preclude “the Government from both punishing a defendant for a criminal offense and forfeiting his property for that same offense in a separate civil *794proceeding.” (518 U.S. at p. 270 [116 S.Ct. at p. 2138, 135 L.Ed.2d at p. 557].) The high court held that, unlike an in personam penalty such as a fine that may constitute punishment, the in rem civil forfeiture of property there at issue never has been considered punitive within the meaning of the double jeopardy clause. The court examined the history of in rem civil forfeitures and observed that, from the earliest times, such forfeitures have been allowed in addition to any related criminal penalties. Ultimately, the court employed a two-part test, asking whether Congress intended the forfeiture proceedings to be criminal or civil, and then considering “whether the proceedings are so punitive in fact as to ‘persuade us that the forfeiture proceeding^] may not legitimately be viewed as civil in nature,’ despite Congress’ intent. [Citation.]” (Id. at p. 288 [116 S.Ct. at p. 2147, 135 L.Ed.2d at p. 568].) Employing this test, the court upheld the civil in rem forfeiture in that case, stating: “\I\n rem civil forfeiture is a remedial civil sanction, distinct from potentially punitive in personam civil penalties such as fines, and does not constitute a punishment under the Double Jeopardy Clause.” (Id. at p. 278 [116 S.Ct. at p. 2142, 135 L.Ed.2d at p. 562].)
The court in Ursery distinguished its holding in Austin on the basis that Austin involved the excessive fines clause of the Eighth Amendment, rather than the double jeopardy clause of the Fifth Amendment. The high court explained that the double jeopardy clause prohibits all types of successive punishment. Thus, the court earlier had held in United States v. Halper (1989) 490 U.S. 435, 442 [109 S.Ct. 1892, 1898, 104 L.Ed.2d 487] that imposition of an in personam civil penalty following the imposition of criminal penalties could violate the double jeopardy clause if the civil penalty is “so extreme and so divorced from the Government’s damages and expenses as to constitute punishment.” The Eighth Amendment, by contrast, prohibits only those fines that are “excessive.” Therefore, “it appears to make little practical difference whether the Excessive Fines Clause applies to all forfeitures ... or only to those that cannot be characterized as purely remedial,” because the excessive fines clause “prohibits only the imposition of ‘excessive’ fines, and a fine that serves purely remedial purposes cannot be considered ‘excessive’ in any event.” (Austin v. United States, supra, 509 U.S. 602, 622, fn. 14 [113 S.Ct. 2801, 2812].) Thus, the method of analysis under the double jeopardy clause differs from that applicable to the excessive fines clause, but both involve the same consideration of whether the penalty serves purely remedial purposes.
In Kansas v. Hendricks (1997) 521 U.S. 346 [117 S.Ct. 2072, 138 L.Ed.2d 501], the United States Supreme Court held that civil commitment under Kansas’s Sexually Violent Predator Act based upon past conduct for which the offender has been convicted and punished does not violate the double jeopardy clause or the ex post facto clause, because such civil commitment *795does not constitute punishment for purposes of either constitutional provision. The first question considered by the court was “whether the legislature meant the statute to establish ‘civil’ proceedings. If so, we ordinarily defer to the legislature’s stated intent.” (Id. at p. 361 [117 S.Ct. at p. 2082, 138 L.Ed.2d at p. 514].) The court found such a legislative intent, adding: “Although we recognize that a ‘civil label is not always dispositive,’ [citation], we will reject the legislature’s manifest intent only where a party challenging the statute provides ‘the clearest proof’ that ‘the statutory scheme [is] so punitive either in purpose or effect as to negate [the State’s] intention’ to deem it ‘civil.’ [Citation.]” (Ibid. [117 S.Ct. at p. 2082, 138 L.Ed.2d at p. 515].) The high court concluded the offender had “failed to satisfy this heavy burden” (ibid.), observing that the state “is not seeking retribution for a past misdeed” (id. at p. 362 [117 S.Ct. at p. 2082, 138 L.Ed.2d at p. 515]), but is acting to protect the public from “the dangerously mentally ill.” (Id. at p. 363 [117 S.Ct. at p. 2083, 138 L.Ed.2d at p. 516].) Concluding that it could not say that the state “acted with punitive intent” in enacting the Sexually Violent Predator Act, the court held “that the Act does not establish criminal proceedings and that involuntary confinement pursuant to the Act is not punitive” within the meaning of the double jeopardy clause or the ex post facto clause. (Id. at p. 369 [117 S.Ct. at p. 2085, 138 L.Ed.2d at p. 519].)
None of the United States Supreme Court decisions discussed above address the precise issue before us. And the method of analyzing what constitutes punishment varies depending upon the context in which the question arises. But two factors appear important in each case: whether the Legislature intended the provision to constitute punishment and, if not, whether the provision is so punitive in nature or effect that it must be found to constitute punishment despite the Legislature’s contrary intent.5 In making these determinations in the present case, we are guided by our recent *796decisions in McVickers and Wright v. Superior Court (1997) 15 Cal.4th 521 [63 Cal.Rptr.2d 322, 936 P.2d 101].
As noted above, we held in People v. McVickers, supra, 4 Cal.4th 81, 88, that requiring a defendant to provide a blood sample for AIDS testing imposes a burden, but is not punitive in nature.-We held that the statutes there under review “have a legitimate purpose other than punishment . . . [and] the method chosen—a mandatory AIDS test with results given only to the defendant and to law enforcement officials—is not excessive in relation to the statute’s asserted purpose.” (Id. at p. 89.) Similarly, in the present case, requiring a defendant to register as a sex offender certainly imposes a burden, but whether the registration requirement constitutes punishment for purposes of ex post facto analysis depends upon whether the purpose or effect of this requirement is punitive in nature.
In Wright v. Superior Court, supra, 15 Cal.4th 521, we recently examined the nature of the sex offender registration requirement imposed by section 290, albeit in another context. We held in Wright that failure to register as required by section 290 is a continuing offense. In so holding, we observed that the sex offender registration requirement “is intended to promote the ‘ “state interest in controlling crime and preventing recidivism in sex offenders.” ’ [Citation.] As this court consistently has reiterated: ‘The purpose of section 290 is to assure that persons convicted of the crimes enumerated therein shall be readily available for police surveillance at all times because the Legislature deemed them likely to commit similar offenses in the future. [Citation.]’ [Citations.] . . . [H] . . . The statute is thus regulatory in nature, intended to accomplish the government’s objective by mandating certain affirmative acts.” (15 Cal.4th at p. 527.)
The sex offender registration requirement serves an important and proper remedial purpose, and it does not appear that the Legislature intended the registration requirement to constitute punishment. Nor is the sex offender registration requirement so punitive in fact that it must be regarded as punishment, despite the Legislature’s contrary intent. Although registration imposes a substantial burden on the convicted offender, this burden is no more onerous than necessary to achieve the purpose of the statute.6 We conclude that the sex offender registration requirement imposed by section 290 does not constitute punishment for purposes of ex post facto analysis.
*797The Court of Appeal reached the opposite conclusion, because it felt bound by this court’s decision in In re Reed, supra, 33 Cal.3d 914.7 We held in Reed that requiring a person convicted of the misdemeanor offense of soliciting “lewd or dissolute conduct” in violation of section 647, subdivision (a), to register as a sex offender constitutes cruel or unusual punishment under the California Constitution (Cal. Const., art. I, § 17).8 In concluding that sex offender registration constitutes punishment for purposes of cruel or unusual punishment analysis, this court applied the factors discussed in Kennedy v. Mendoza-Martinez, supra, 372 U.S. 144 and concluded that the registration requirement is “an affirmative disability or restraint.” (In re Reed, supra, 33 Cal.3d 914, 920.) The court in Reed recognized that sex offender registration has not “ ‘historically been regarded as punishment,’ ” but found that was “not dispositive.” (Id. at p. 921.) The court also stated that registration comes into play only on a finding of scienter, that it promotes the traditional aims of punishment, and that the behavior to which it applies already is a crime. Turning to whether the requirement has “ ‘an alternative purpose’ ” other than punishment, the court in Reed recognized that “the Legislature may reasonably have intended that sex offender registration serve as a law enforcement tool to facilitate criminal investigations,” but questioned whether it is “effective in practice” and found this factor was “outweighed here by the fact that the penalty of registration is ‘excessive in relation to the alternative purpose assigned’ to it.” (Id. at p. 922, fn. omitted, italics in original.)
As noted above, subsequent to our decision in Reed, the United States Supreme Court elaborated upon and refined the criteria to be considered in determining whether a provision should be considered “punishment” for purposes of ex post facto analysis (see, e.g., Kansas v. Hendricks, supra, 521 U.S. 346, 361-369 [117 S.Ct. 2072, 2081-2086, 138 L.Ed.2d at pp. 515-519] [indefinite civil commitment of a sexually violent offender does not constitute punishment for ex post facto purposes]), and our court also has spoken *798directly to the issue (see, e.g., People v. McVickers, supra, 4 Cal.4th 81 [requiring a convicted felon to submit to an AIDS test does not constitute punishment for ex post facto purposes]). Upon reexamination of the decision in Reed in light of these more recent cases, we conclude that Reed should be disapproved to the extent that decision can be interpreted as suggesting that sex offender registration constitutes punishment for purposes of ex post facto analysis.
To begin with, in this context, we believe it is appropriate to place greater emphasis than did the court in In re Reed, supra, on the circumstance that sex offender registration has not “ ‘historically been regarded as punishment.’ ” (33 Cal.3d at p. 920.) While not dispositive, this factor is of great importance, because it supports the conclusions that the Legislature did not intend the provision to constitute punishment and that the provision is not punitive in nature. As noted above, virtually every other jurisdiction that has passed on the question has concluded that sex registration provisions are regulatory rather than punitive, and do not constitute punishment for purposes of the ex post facto doctrine. (See ante, at p. 792.) As we have explained, our recent decision in Wright v. Superior Court, supra, 15 Cal.4th 421, makes it clear that the registration provision is regulatory in nature.
Second, because the question at issue in In re Reed, supra, involved whether sex registration was “cruel or unusual punishment” as applied to the misdemeanor solicitation conviction of which the defendant in that case had been convicted, the court in Reed directed much of its consideration to whether the registration requirement was “excessive” in light of a statement made by the Los Angeles City Attorney, who appeared as amicus curiae in Reed. This statement maintained that “mandatory registration of section 647(a) misdemeanants as sex offenders is ‘dysfunctional,’ ” because it overloads law enforcement computers with useless information and imposes a disability out of proportion to the relatively minor offense that triggered its application. (33 Cal.3d at p. 922, fn. 7, italics added.) These considerations do not apply in the present case. Further, because Reed addressed a claim of cruel or unusual punishment, the central issue was whether the registration requirement was excessive or disproportionate to the severity of the offenses committed by the defendant in Reed. The present case, by contrast, involves an ex post facto claim in which the excessiveness of the registration requirement in relation to its purpose is only one factor of several to be considered.
Accordingly, to the extent that the analysis in Reed can be understood, as the Court of Appeal in the present case viewed that decision, *799to indicate that the sex offender registration requirement should be considered “punishment” for purposes of ex post facto analysis, Reed’s analysis is disapproved.9 .
In sum, we conclude that sex offender registration does not constitute punishment for purposes of ex post facto analysis, because the Legislature did not intend such registration to constitute punishment and the provision is not so punitive in nature or effect that it must be held to constitute punishment despite the Legislature’s contrary intent.
III
Defendant additionally contends that even if requiring him to register as a sex offender does not violate the ex post facto clause, the trial court’s order nonetheless is invalid, because the court failed to state its reasons for ordering him to register as a sex offender as required by section 290, subdivision (a)(2)(E). As noted above, this subdivision requires persons convicted of an offense not specified in section 290 to register as a sex offender “if the court finds . . . that the person committed the offense as a result of sexual compulsion or for purposes of sexual gratification.” Subdivision (a)(2)(E) further provides: “The court shall state on the record the reasons for its findings and the reasons for requiring registration.”
Although defendant raised this issue on appeal, the Court of Appeal expressly declined to reach the issue, because of its decision striking the trial court’s order requiring sex offender registration as violative of the ex post facto clause. On remand, the Court of Appeal should consider this issue.
IV
The judgment of the Court of Appeal is reversed, and the matter is remanded to that court for further proceedings consistent with the views expressed in this opinion.
Baxter, J., and Chin, J., concurred.
A11 further undesignated statutory references are to the Penal Code.
As enacted, subdivision (a)(2)(E) of section 290 included among the persons required to register as a sex offender: “Any person ordered by any court to register pursuant to this section for any offense not included specifically in this section if the court finds at the time of conviction that the person committed the offense as a result of sexual compulsion or for purposes of sexual gratification. The court shall state on the record the reasons for its findings and the reasons for requiring registration.” (Stats. 1994, ch. 867, § 2.7.) The section later was amended to provide that the required finding could be made at the time of conviction or sentencing. (Stats. 1998, ch. 930, § 1.1.)
In People v. Franklin (1999) 20 Cal.4th 249, 253 and footnote 2 [84 Cal.Rptr.2d 241, 975 P.2d 30], we held that “failure to comply with California’s sex offender registration law constitutes a penal offense," but “express[ed] no opinion on whether the obligation that a person register as a sex offender, imposed as a consequence of a conviction of a criminal offense, constitutes punishment for purposes of ex post facto analysis,” noting that that issue is before us in the present case.
In addressing this question, the high court explained that the decisions in Kennedy v. Mendoza-Martinez, supra, 372 U.S. 144, and United States v. Ward (1980) 448 U.S. 242 [100 S.Ct. 2636, 65 L.Ed.2d 742] did not govern the determination of whether a provision constitutes punishment for purposes of the excessive fines clause of the Eighth Amendment: “The question in those cases was whether a nominally civil penalty should be reclassified as criminal and the safeguards that attend a criminal prosecution should be required. [Citations.] In addressing the separate question whether punishment is being imposed, the Court has not employed the tests articulated in Mendoza-Martinez and Ward. [Citation.]” (Austin v. United States, supra, 509 U.S. 602, 610, fn. 6 [113 S.Ct. 2801, 2806].) The court focused, instead, upon “whether, at the time the Eighth Amendment was ratified, forfeiture was understood at least in part as punishment and whether forfeiture under §§ 881(a)(4) and (a)(7) should be so understood today.” (Id. at pp. 610-611 [113 S.Ct. at p. 2806].)
Although, as we have noted, virtually every other court that has addressed the issue has concluded that sex offender registration does not constitute “punishment” for purposes of the ex post facto clause, there is some disagreement in the cases as to whether the multifactor test articulated in Kennedy v. Mendoza-Martinez, supra, 372 U.S. 144, applies in this context. (Compare Artway v. Attorney General of State ofN.J. (3d Cir. 1996) 81 F.3d 1235, 1261-1263 [questioning applicability of Mendoza-Martinez]; Opinion of the Justices to the Senate (1996) 423 Mass. 1201 [668 N.E.2d 738, 749] [same]; Doe v. Poritz, supra, 662 A.2d 367, 399-404 [same] with State v. Noble, supra, 829 P.2d 1217, 1221-1224 [applying Mendoza-Martinez factors]; State v. Ward (1994) 123 Wn.2d 488 [869 P.2d 1062, 1068-1074] [same]; State v. Myers (1996) 260 Kan. 669 [923 P.2d 1024, 1033-1043] [same].) Other courts have reached the same conclusion without discussing the applicability or inapplicability of the Mendoza-Martinez factors. (See, e.g., Kitze v. Com. (1996) 23 Va.App. 213 [475 S.E.2d 830, 832-833]; State v. Costello, supra, 643 A.2d 531.)
We believe there is no need to resolve that issue here, because all of the cases recognize that the two factors noted above—whether the Legislature intended the provision to constitute punishment, and, if not, whether the provision is nonetheless so punitive in nature and effect *796that it must be found to constitute punishment despite the Legislature’s contrary intent—are the crucial elements to be considered.
It does not appear that defendant is subject to the public notification provisions of section 290, subdivisions (m) and (n), and section 290.4, and we express no opinion regarding the effect, if any, that application of those provisions would have upon our analysis.
Although defendant argued successfully in the Court of Appeal that requiring him to register as a sex offender violates the ex post facto clauses of the California and federal Constitutions, causing the Court of Appeal to strike the registration order, defendant now concedes that “the trial court’s order requiring appellant to register as a sex offender does not violate this Court’s construction of the ex post facto clause.” Defendant reasons that “[i]n light of this Court’s recent opinion in Wright v. Superior Court (1997) 15 Cal.4th 521, it appears that this Court has already overruled the holding of In re Reed (1983) 33 Cal.3d 914.” Defendant goes on to argue, however, that “[njothing in the federal Constitution requires that Reed be overruled,” citing Collins, Austin, and Ursery. On this issue, the gauntlet has been picked up by amicus curiae, which argues that our decision in Reed compels the conclusion that the trial court’s order violates the ex post facto clauses of both the federal and California Constitutions.
Two years later, the Legislature amended section 290 to delete the registration requirement for persons convicted of violating section 647, subdivision (a). (Stats. 1985, ch. 929, § 4, p. 2936, ch. 1474, § 1, p. 5403.)
Our statement in People v. McClellan (1993) 6 Cal.4th 367, 380 [24 Cal.Rptr.2d 739, 862 P.2d 739] that sex offender registration is an “element of punishment for the underlying offense” (in the context of a plea agreement) does not alter our analysis. That statement in McClellan was based upon an earlier citation to Reed. (6 Cal.4th at p. 374.) The decision in McClellan did not address whether the sex offender registration requirement imposed by section 290 constitutes punishment, and “an opinion is not authority for a proposition not therein considered.” (Ginns v. Savage (1964) 61 Cal.2d 520, 524, fn. 2 [39 Cal.Rptr. 377, 393 P.2d 689].)