Defendants appeal from a judgment which granted a peremptory writ of mandate directing the State Board of Education to reinstate plaintiff’s credentials as a teacher and requiring the Board of Education of the City and *171County of San Francisco to reinstate plaintiff to his position in the public schools of San Francisco. His credentials were revoked and he was dismissed from his position on the theory that this action was required by sections added to the Education Code effective as of July 2,1952, which in general prohibit the employment in public schools of persons convicted of certain sex offenses defined in specified sections of the Penal Code and the Welfare and Institutions Code.1 (Stats. 1953, 1st Ex. Sess. 1952, ch. 25, p. 389.) The principal question presented on this appeal is whether the legislation is to be applied retrospectively to a person convicted prior to its enactment.
In December 1945, over six years before adoption of the legislation, plaintiff was charged in the Municipal Court of the Los Angeles Judicial District with “a misdemeanor, to wit: vagrancy lewd,” and, after pleading guilty, was sentenced and paid a fine of $50. Although the docket of the criminal trial does not disclose whether the conviction was for violation of a statute referred to in the 1952 legislation, we may assume, in view of the pleadings here, that it was for violation of one of those statutes, namely, subdivision 5 of section 647 of the Penal Code which, at that time, provided that every “idle, or lewd, or dissolute person, or associate of known thieves” was a vagrant and guilty of a misdemeanor.2
Prior to January 1949 plaintiff received a general elemen*172tary school credential, and in that month, more than three years before enactment of the legislation in question, he was employed as a teacher by the San Francisco Unified School District. He acquired tenure and remained a teacher in the district until the date of his dismissal. A special teaching credential issued to him by the state in 1951 was renewed on April 30, 1953.
The record does not show when the fact of plaintiff’s conviction was discovered, but he was dismissed without notice or hearing on September 28, 1953, and his credentials were revoked on October 29. His petition for mandate, filed in December 1953, alleged in part that the action taken against him was invalid because it was without notice or hearing. Judgment was entered for plaintiff on this ground, and we reversed, holding that no notice or hearing was required. (DiGenova v. State Board of Education (1955) 45 Cal.2d 255 [288 P.2d 862].) Subsequently it was held in Fountain v. State Board of Education (1958) 157 Cal.App.2d 463 [320 P.2d 899] (hearing denied by this court) that the legislation involved here was not intended to apply retrospectively to persons convicted of a sex offense prior to the effective date of the statute. In rendering the judgment from which the present appeal was taken, the trial court followed the rule laid down in the Fountain case and held that defendants exceeded their jurisdiction in revoking plaintiff’s credentials and terminating his employment.
It is specifically provided in three of our basic codes that no part thereof is retroactive “unless expressly so declared.” (Civ. Code, § 3 ; Code Civ. Proc., § 3 ; Pen. Code, § 3.) This is a rule of construction originally developed by the courts. In People v. Harmon, 54 Cal.2d 9, 25 [351 P.2d 329], it was said that section 3 of the Penal Code, supra, “is but a restatement of a ‘general rule of statutory construction’ (Von Schmidt v. Huntington (1850) 1 Cal. 55, 65) recognized by the Code Commissioners by their citation of that and kindred cases. ’ ’ Similar statements appear in In re Cate, 207 Cal. 443, 448-449 [279 P. 131], and in Estate of Potter, 188 Cal. 55, 65 [204 P. 826]. Accordingly, where language used by the Legislature has not clearly shown that retroactive application was intended, the rule against retroactive construction has uniformly been held applicable to codes or acts not containing the provision set forth in the Civil Code, the Code of Civil Procedure, and the Penal Code. (State v. Industrial Acc. Com., 48 Cal.2d 355, 361-362 [310 P.2d 1] [Labor *173Code] ; Aetna Cas. & Surety Co. v. Industrial Acc. Com., 30 Cal.2d 388, 393-395 [182 P.2d 159] [Labor Code] ; Krause v. Rarity, 210 Cal. 644, 655-656 [293 P. 62, 77 A.L.R. 1327] [former California Vehicle Act] ; In re Cate, 207 Cal. 443, 448-449 [279 P. 131] [State Bar Act] ; Estate of Potter, 188 Cal. 55, 65, 68 [204 P. 826] [former Inheritance Tax Act] ; Chambers v. Gibb, 186 Cal. 196, 199 [198 P. 1032] [former Inheritance Tax Act] ; Willcox v. Edwards, 162 Cal. 455, 460-461 [123 P. 276, Ann.Cas. 1913C 1392] [amendment to the Constitution] ; Bascomb v. Davis, 56 Cal. 152, 156 [federal act] ; Gates v. Salmon (1865) 28 Cal. 320, 321-323 [former Practice Act].)
It is thus clear that the absence of the statutory provision from other codes and statutes, including the Education Code, does not indicate that with respect to those enactments the Legislature has rejected the rule against a retroactive construction or that some different rule is applicable. The rule to be applied is the same with respect to all statutes, and none of them is retroactive unless the Legislature has expressly so declared.
The statement in the Education Code that its provisions are to be liberally construed with the view to effect its objects and promote justice (§2) cannot be interpreted as a declaration that any of its sections is to be given retroactive effect. Aetna Cas. & Surety Co. v. Industrial Acc. Com., 30 Cal.2d 388 [182 P.2d 159], involved the question whether an amendment to the Workmen’s Compensation Act increasing benefits to injured employees could be construed as retroactive in the absence of an express declaration. The Labor Code directs (§ 3202) that its provisions governing workmen’s compensation are to be “liberally construed by the courts with the purpose of extending their benefits for the protection of persons injured in the course of their employment.” It was argued that in view of this declaration and decisions holding that all reasonable doubt must be resolved in favor of the employees, the amendment should be given retroactive application. In rejecting this argument, the Aetna opinion stated (30 Cal.2d at p. 395) •. “No authority is cited for this novel doctrine which would require the court to ignore the rule against retroactive operation with respect to statutes increasing benefits to persons favored by remedial legislation. The rule of liberal construction and the rule that statutes should ordinarily be construed to operate prospectively are neither inconsistent nor mutually exclusive. They *174relate to different aspects of the interpretation of statutes, and are found in most of the codes, including the Labor Code. (Civ. Code, §§ 3, 4 ; Code Civ. Proe., §§ 3, 4 ; Pen. Code, §§ 3, 4 ; Lab. Code, §§ 4, 3202.) It would be a most peculiar judicial reasoning which would allow one such doctrine to be invoked for the purpose of destroying the other. It seems clear, therefore, that the legislative intent in favor of the retrospective operation of a statute cannot be implied from the mere fact that the statute is remedial and subject to the rule of liberal construction.”3
State v. Industrial Acc. Com., 48 Cal.2d 355, 361-362 [310 P.2d 1], also involved the question of whether an amendment to the workmen’s compensation provisions of the Labor Code was retroactive. It was there pointed out that nowhere in the amendment had the Legislature declared that it should be given retroactive operation, and the court concluded that the claim of retroactivity was unsound notwithstanding the fact that the legislation was remedial and curative in character and was based on legislative declarations and findings concerning public policy and public welfare and the inequity existing under the law prior to the amendment.
It is settled therefore that no statute is to be given retroactive effect unless the Legislature has expressly so declared and that this rule is not limited by a requirement that a statute be liberally construed to effect its objects and promote justice.
We come now to a consideration of the provisions of the 1952 legislation which were applied retroactively by defendants in revoking plaintiff’s credentials.
Section 13207 of the Education Code provides: “Whenever the holder of any credential, life diploma, or document issued by the State Board of Education has been convicted of any sex offense as defined in Section 12912, the State Board of Education shall forthwith suspend the credential, life diploma, or document. If the conviction is reversed and the holder is acquitted of the offense in a new trial or the charges against him are dismissed, the board shall forthwith terminate the suspension of the credential, life diploma, or document. When *175the conviction becomes final or when imposition of sentence is suspended the board shall forthwith revoke the credential, life diploma, or document.”4
The quoted section, considered as a whole, shows a plan of first suspending credentials immediately upon conviction and then, subsequent to events occurring after the effective date of the enactment, revoking them, and this plan would not be applicable to convictions which became final prior to 1952. As appears from the first sentence the preliminary step of suspension, which, of course, could occur only after the effective date of the enactment, must be taken “forthwith” after conviction. The second sentence shows that the convictions referred to are subject to reversal after the effective date of the enactment, followed by acquittal or dismissal of charges. The last sentence contemplates that revocation of credentials shall take place only with respect to cases in which a conviction “becomes” final or in which imposition of sentence “is suspended,” i.e., events occurring after enactment of the section. The language “has been convicted” (in the present perfect tense), which appears in the first sentence of the section, is not helpful in determining the question of retroactivity. The act is a direction to the persons charged with administering it, and when viewed as of the time the act is being applied the quoted words can as readily be understood either as “has been convicted after the effective date of the act” or as “has been convicted before or after the effective date of the act.” Nothing in the section points in the direction of retroactive application, and certainly none of its language constitutes an express declaration that the statute should operate retroactively.
Section 13255, relating to certified employees, provides: “Governing boards of school districts shall not employ or retain in employment persons in public school service who have been convicted of any sex offense as defined in Section 12912. If, however, any such conviction is reversed and the person is acquitted of the offense in a new trial or the charges against him are dismissed, this section does not prohibit his employment thereafter.”5
*176Section 13255 shows a pattern or approach somewhat like the one taken in section 13207 in that the operation of this section is affected by events occurring after the effective date of the act, such as reversal followed by acquittal. As in the case of the words “has been convicted” in section 13207, the words “have been convicted” in section 13255 in no way indicate an intent that the provisions apply retroactively.
Such an intent is not suggested by the phrase “retain in employment”; it shows only that the act applies to those employed in the public schools when convicted as well as to those seeking employment after conviction. Again nothing in the section points in the direction of retroactive application, nor does it contain an express declaration of retroactivity as required by the settled law of this state.
The Legislature, of course, is well acquainted with this fundamental rule, and when it intends a statute to operate retroactively it uses clear language to accomplish that purpose. For example, section 290 of the Penal Code, which, like the legislation before us, relates to collateral consequences of convictions of certain sex offenses, has provided from the time of its enactment in 1947 that any person who, “since the first day of July, 1944, has been or is hereafter convicted” of the enumerated offenses shall register with the chief of police or sheriff where he resides. Similarly, in 1955 subdivision (i) was added to section 13129 of the Education Code to provide for permissive rather than mandatory denial of credentials for convictions of violating subdivision 1 of section 311 of the Penal Code (indecent exposure) occurring “prior to the effective date” of the provision.6
Defendants invoke reports of the Assembly Subcommittee on Sex Crimes (one made before and the other after the legislative session at which the statute in question was enacted) to show the Legislature intended that the 1952 provisions should have a retroactive effect. Such reports, however, cannot supplant the established statutory and common-law requirement that no provision of a statute is retroactive *177unless expressly so declared. Even if the reports could be so invoked, they do not discuss the question of retroactive application or contain anything showing that such an application was intended. The Preliminary Report submitted on March 8,1950, states (at p. 9) that the problem of sex crimes has two major aspects, the protection of the community and the control, correction, or treatment of the individual offender. Although the term “sex offender” was described as meaning “past” offender (Prelim. Rep., p. 30), this was done to differentiate such an offender from the “future sex offender,” described as a person who probably will commit a sex crime (Prelim. Rep., pp. 32-33), and not to indicate the desirability of retroactive measures. The report submitted in August 1952 after the effective date of the legislation stated at page 42 that “a person convicted of a sex offense should not continue to be employed in the Public School System.” As we have seen, words such as “retain in employment” do not indicate retroactivity, and the same is true of the comparable words in the report, “continue to be employed.” Moreover, in making this statement subsequent to the enactment of the legislation the subcommittee was considering, not the question of retroactivity, but rather, as shown by the next sentence in the report, the question whether a convicted employee should be allowed “to terminate from one school district and to then obtain employment at another school. ’ ’
It is also urged by defendants that retroactive application of the legislation before us is essential for the adequate protection of school children. This was a policy matter for the Legislature to consider. When the statutes in question were enacted in 1952 there were already provisions in existence, which are still operative, for excluding from the school system persons dangerous to children by reason of sexual misconduct. Under these provisions any dangerous person can be excluded from teaching on grounds such as “evident unfitness” (e.g., Ed. Code, §§ 13202, 13209), and, of course, it would be appropriate under them to consider a conviction of a sex offense regardless of when it occurred. It is true that the 1952 legislation is more sweeping than these provisions in that it imposes a mandatory duty to take action, without notice or hearing, against a person coming within its terms even though he may have evidence that he has been rehabilitated and is presently fit to be a teacher. However, it is fallacious to suggest that, unless the 1952 *178legislation is held to operate retroactively, school children will be left without protection. In view of the protection afforded by the other provisions the Legislature may have concluded that retroactive application of the 1952 legislation was undesirable because it would automatically, irrespective of what showing could be made of rehabilitation and present fitness, result in destroying the means of livelihood of persons having no warning of this consequence until after their conviction. Whether the Legislature was influenced by these considerations or by others, the fact remains that it used no language expressing an intent to make the legislation apply retroactively.
The question whether the 1952 legislation was retroactive was squarely presented in Fountain v. State Board of Education, supra, 157 Cal.App.2d 463, which held that it does not apply to persons convicted of sex offenses before its effective date. The decision that the teacher was entitled to reinstatement rested solely on the determination with respect to retro-activity, since the only other question involved in the case was resolved against him. We unanimously denied a petition for hearing in that case. Although this court’s denial of a hearing is not to be regarded as expressing approval of the propositions of law set forth in an opinion of the District Court of Appeal or as having the same authoritative effect as an earlier decision of this court (Western Lithograph Co. v. State Board of Equalization, 11 Cal.2d 156, 167-168 [78 P.2d 731, 117 A.L.R. 838] ; Bohn v. Bohn, 164 Cal. 532, 537-538 [129 P. 981] ; People v. Davis, 147 Cal. 346, 350 [81 P. 718]), it does not follow that such a denial is without significance as to our views (see Cole v. Rush, 45 Cal.2d 345, 351, fn. 3 [289 P.2d 450, 54 A.L.R.2d 1137] ; Eisenberg v. Superior Court, 193 Cal. 575, 578 [226 P. 617]). Cole v. Rush quoted with approval the following statement from the Eisenberg case (at p. 578) : “The order of this court denying a petition for a transfer . . . after . . . decision of the district court of appeal may be taken as an approval of the conclusion there reached, but not necessarily of all of the reasoning contained in that opinion.” It should be noted that the Department of Education, acting on the basis of the Fountain decision, reinstated several persons whose credentials had been revoked for pre-1952 convictions and that, although the case was decided in February 1958, the Legislature has not seen fit to make any amendment to overcome its effect.
There is no merit to the contention that the decision *179of this court upon the prior appeal (DiGenova v. State Board of Education, 45 Cal.2d 255 [288 P.2d 862]) constitutes the law of the case so as to preclude us from holding as to plaintiff that the 1952 legislation is not retroactive. The doctrine of the law of the case does not extend to points of law which might have been but were not presented and determined on a prior appeal. (Steelduct Co. v. Henger-Seltzer Co., 26 Cal.2d 634, 644 [160 P.2d 804] ; Moore v. Trott, 162 Cal. 268, 273 [122 P. 462] ; Trower v. City & County of San Francisco, 157 Cal. 762, 765 [109 P. 617] ; Skaggs v. City of Los Angeles, 138 Cal.App.2d 269, 273 [291 P.2d 572, 292 P.2d 572] ; Webb v. Saunders, 89 Cal.App.2d 732, 736 [201 P.2d 816].) The opinion of this court in 45 Cal.2d was limited to the question whether plaintiff could properly be dismissed without notice or hearing. It contained nothing upon the question of retroactive construction but, to the contrary, stated that “on retrial plaintiff may show that the boards exceeded their authority in that the convictions were not those contemplated by section 12756 [now § 13207] or that he was not the person convicted.” This language is clearly broad enough to permit consideration, upon retrial, of the question presented here, because the offense of which plaintiff was convicted would be among “those contemplated by” the legislation only if the legislation is construed as retrospective.
Moreover, the doctrine of the law of the case, which is merely a rule of procedure and does not go to the power of the court, has been recognized as being harsh, and it will not be adhered to where its application will result in an unjust decision. (Vangel v. Vangel, 45 Cal.2d 804, 809-810 [291 P.2d 25, 55 A.L.R.2d 1385] ; England v. Hospital of Good Samaritan, 14 Cal.2d 791, 795-796 [97 P.2d 813] ; see Gore v. Bingaman, 20 Cal.2d 118, 122-123 [124 P.2d 17].) In the England case this court held that it would be unjust to apply the doctrine against a plaintiff where the law (relating to liability of charitable hospitals) had been “unsatisfactory in its statement” at the time of several prior appeals but was clarified, so as to permit recovery, in another case filed on the same day the England case was decided. The court declared that to refuse to apply the newly adopted rule to the plaintiff would “exalt form far above substance” and would result in a “most unjust decision.” (14 Cal.2d at pp. 795-796.) The exception made in the Englandl case has also been applied to cases where the controlling rules of law have been altered or clarified by a decision intervening between the first *180and second determinations of the appellate courts. (Subsequent Injuries Fund v. Industrial Acc. Com., 53 Cal.2d 392, 394-395 [348 P.2d 193] ; see Gore v. Bingaman, 20 Cal.2d 118, 122-123 [124 P.2d 17] ; Standard Oil Co. v. Johnson, 56 Cal.App.2d 411, 416 [132 P.2d 910].) The decision in Fountain v. State Board of Education, supra, 157 Cal.App.2d 463, was made between the prior appeal and the second trial in the present case, and, as noted above, the state board, acting on the basis of Fountain, restored credentials to several persons who had lost them as a result of the 1952 legislation. It is obvious that application of the doctrine here would result in a manifest injustice.
The local board asserts that at the second trial the court erred in denying its motion to dismiss for lack of jurisdiction. Section 583 of the Code of Civil Procedure requires that a case must be brought to trial within three years after the remittitur issued on appeal is filed in the trial court, and the position of the local board is that this requirement was not met because the proceedings instituted by plaintiff within the three-year period did not comply with the provisions of section 594 of the Code of Civil Procedure for a five-day notice of trial on an “issue of fact.”7 However, the answer of defendants admitted that the conviction occurred prior to 1952, and the issue of retroactivity presented only a question of law. No factual determinations were necessary to establish plaintiff’s right to reinstatement, and the five-day notice requirement was inapplicable.8 The trial court thus correctly denied the local board’s motion to dismiss. A different situation was presented by plaintiff’s request for damages, which involved questions of fact. Although the city was entitled to the five-day notice insofar as concerns trial of this issue, plaintiff submitted the case to the trial court for decision upon the sole issue of reinstatement, announcing that he was not then prepared to offer proof of damages, and the judgment does *181not award damages. Plaintiff, who argues that the ease should be remanded in order to try the issue of damages, is in no position to raise this point since he has not appealed.
The judgment is affirmed.
Traynor, J., Peters, J., White, J., and Dooling, J., concurred.
The sections of the legislation in question were renumbered in 1959, and they will be referred to in this opinion by their new numbers.
Section 12912 of the Education Code provides: “ 'Sex offense’ as used in Sections 13130, 13207, 13218, 13255, and 13586 of this code means any offense defined in Sections 266, 267, 285, 286, 288, 288a, 647a, subdivision 3 or 4 of Section 261, subdivision 5 of Section 647, or subdivision 2 of Section 311 of the Penal Code; or any offense defined in subdivision 1 of Section 311 of the Penal Code committed on or after the effective date of the amendment of this section made at the 1955 Regular Session by the Legislature; or any offense involving lewd and lascivious conduct under Section 702 of the Welfare and Institutions Code; or any attempt to commit any of the above-mentioned offenses; or any offense committed or attempted in any other state which, if committed or attempted in this State, would have been punishable as one or more of the above-mentioned offenses. ’ ’
The other pertinent sections added in 1952 will be set forth later.
In May 1947 plaintiff was convicted of violating section 41.10 of ordinance 77000 of the City of Los Angeles, which prohibited a person from renting a room with the understanding or belief that the room is to be used by the person to whom it is rented for certain purposes, including lewd conduct. This conviction, however, has no bearing upon the present ease because the statutes involved here do not direct mandatory revocation of teaching credentials or dismissal from employment for violations of ordinances.
Section 4 of the Labor Code, cited in the Aetna case to show that the rule against retroactive construction was operative notwithstanding the rule of liberal construction, is identical to section 22 of the Education Code. These sections provide: “No action or proceeding commenced before this code takes effect, and no right accrued, is affected by the provisions of this code, but all procedure thereafter taken therein shall conform to the provisions of this code so far as possible.' ’
Section 13218, which is not applicable to plaintiff because it deals with suspension and revocation by county boards of county-issued certificates, contains language similar to that found in section 13207.
Similar language is contained in section 13586, which is inapplicable to plaintiff because it relates to “classified” employees, i.e., those in positions not requiring certification qualifications.
In view of this change it was necessary to amend section 12912, which, as enacted in 1952, included convictions of indecent exposure for purposes of the mandatory legislation before us. Accordingly, by a companion measure section 13912 was amended, insofar as concerns violations of subdivision 1 of section 311 of the Penal Code, to refer only to offenses committed "on or after the effective date of the amendment of this section made at the 1955 Regular Session by the Legislature. ..." The quoted language was added to section 12912 for the special purpose of making a clear contrast with the new provision for permissive action and avoiding conflict between that provision and the 1952 legislation.
Section 594 of the Code of Civil Procedure provides in part: “1. In superior courts and municipal courts either party may bring an issue to trial or to a hearing, and, in the absence of the adverse party, unless the court, for good cause, otherwise direct, may proceed with his case, and take a dismissal of the action, or a verdict, or judgment, as the ease may require; provided, however, if the issue to be tried is an issue of fact, proof must first be made to the satisfaction of the court that the adverse party has had five days notice of such trial.”
There may, of course, be a “trial” where only issues of law are determined. (Cf. Carney v. Simmonds, 49 Cal.2d 84, 90 [315 P.2d 305] ; O’Day v. Superior Court, 18 Cal.2d 540, 544-545 [116 P.2d 621] ; City of Pasadena v. Superior Court, 212 Cal. 309, 313-314 [298 P. 968].)