Full opinion text
PETERS, P. J. In 1932 the Board of Education of the City and County of San Francisco hired Wilbur S. Owensby to. examine and audit the- books, records and accounts of the school department, with particular regard to the service status rating classification and salary of all of the teachers in the department. In San Francisco salaries of teachers are fixed by a salary schedule, the amount of salary being dependent and rated according to years of service. Owensby made an exhaustive investigation and audit, and reported to the board that all of the 189 teachers involved in'these proceedings had been overrated due to errors of various kinds, and consequently overpaid for periods varying from one to more than ten years prior to 1932. He recommended that the service status rating of each of these teachers be re-rated downward in accordance with his interpretation of the rules of the board in effect when these teachers were first employed. Some of the errors in rating were due to errors in calculation made by employees of the board, either purely mechanical or caused by errors in interpretation or application of the rules of the board, while others were due to the fact that when these teachers were first hired they were given by the board as it was then constituted ratings, which, according to Owensby’s views, were too high and in violation of the rules of the board as they then existed. The board in 1932 adopted Owensby’s recommendations. It proceeded to re-rate these 189 teachers downward, and also took steps to recover from such teachers the amount of the alleged over-payments for a period of two years next preceding July 1, 1932, that being* the date of the beginning of the next succeeding school year. Although; in most cases, the alleged errors in rating had occurred more than two years prior to the re-rating of 1932, the charge back was limited to two years on the theory that recovery of excess payments beyond that period was barred by the statute of limitations. The revised rating was also applied in making salary payments for the school year commencing July 1, 1932, and for all subsequent years. The net result of the action of the board in 1932 was that these 189 teachers had deducted from their salaries in installments substantial sums of money alleged to have been overpaid them for the period 1930-1932, and, for the period starting July 1, 1932, their ratings, and consequently their salaries, were substantially reduced below what their ratings were in 1931-1932, and prior thereto. The teachers affected protested the deductions and reductions in salary, and immediately instituted these eight mandamus proceedings which have been consolidated. In these actions the 189 teachers affected seek the recovery of the amounts charged back against their salaries as excess payments for the period 1930-1932, and also seek by mandamus to compel the board to give to them for the school year starting July 1, 1932, and thereafter, the ratings they had prior to the re-rating of 1932. After a lengthy trial (the reporter’s transcript contains 3425 pages), the trial judge, the Honorable C. J. Goodell, prepared two opinions in which he discussed the law and the facts applicable to each of the litigants. Thereafter complete and carefully prepared findings and conclusions of law were filed. Generally speaking 'the trial court divided the 189 teachers into three main groups. As to group one, involving the so-called “mechanical” error cases (which group is, itself, divided into several distinct categories hereafter discussed), it was held that the teachers included therein could neither recover the amounts charged back against their salaries, nor were they entitled to be restored to their ratings as they existed prior to the re-rating of 1932. The court found that these teachers had been rated too high due to “mechanical and clerical errors,” of employees of the board, mainly of the paymaster’s department, without authorization by the board. It was held that the board was legally required to place the teachers in this group on their correct salary rating as soon as the errors were discovered, and to collect back all overpayments based on the alleged errors not barred by the statute of limitations. As to the second group, involving the so-called “non-uniformity” eases (also divided into several categories hereafter discussed), the court found that the teachers included therein were entitled to recover the alleged excess payments charged back against tneir salaries, but, that the board could and did lawfully re-rate them downward effective as of the commencement of the school year 1932-1933. In other words, as to this group it was held, that the board could change its ratings prospectively, but it could not do so retroactively. The third group included but six teachers. As to them the trial court held that because of facts peculiar to their individual cases the board was estopped from charging back the allegedly excess payments and from changing their ratings prospectively for the school year 1932-1933, and thereafter. In other words, it was held that, regardless of any error that may have been committed when the teachers were originally rated, the board, because of facts peculiar to each of the six cases, was estopped from re-rating these teachers either prospectively or retroactively. The teachers in the first group appeal from the judgment insofar as it denies them relief both prospectively and retroactively. Their main contentions are that there were no errors in the original ratings, but even if there were, the teachers had a vested right in the original ratings; that the board had no lawful right to interfere with that vested right; that the board ratified the errors, if any there were; that the board is now estopped to claim error. The teachers in the second group appeal from the judgment insofar as it sustained the right of the board to re-rate them prospectively for the year commencing July 1,1932. The teachers here involved make the same contentions as those in the first group, and, in addition, point out that every teacher in this group had his or her original rating fixed by formal resolution of the board. It is contended that the board as it was constituted in 1932 had no lawful right to overrule or change a right granted by an earlier board in the exercise of its discretion. The board appeals from the judgment insofar as it sustains the right of the teachers in this group to recover amounts charged back against current salary. The main thought of the board is that these teachers were originally erroneously rated, and that it was the duty of the board, upon discovering the error, not only to re-rate them prospectively but to recover overpayments based upon the error. The board appeals from the judgment in favor of the six teachers in the third group, it being contended that no lawful basis for an estoppel exists. Before directly discussing the contentions of the parties some reference must be made to the salary schedule of the school department and to the rules applicable thereto. The salaries of certificated personnel in the school department are not fixed by separate contract with each employee. Such salaries are fixed by a salary schedule, the amount of salary being dependent upon years of service. Each year, between May 1st and May 21st, the board, acting pursuant to the provisions of the city charter and of the School Code, adopted a schedule of salaries for teachers for the next ensuing school year, which starts on July 1st. Such schedules when once worked out were not changed each year. Frequently the board would readopt the schedule for the preceding year. For the school year 1925-1926 a new salary schedule was adopted. That schedule was readopted each succeeding year until 1930-1931 when a new schedule was adopted. This last mentioned schedule remained in effect through the school year 1932-1933. These schedules fixed the salaries of the teachers in the several divisions of the school system, a separate schedule being set forth for teachers in the elementary schools, continuation or part-time high schools, junior high schools, attendance officers and senior high schools. In these schedules the salary of each teacher depends upon her “service status rating,” which in turn depends upon her years of service. The 1925-1926 schedule has twelve “service status ratings” for each division, designated 1st through 12th, except that the ratings for attendance officers stop at 9th. The schedule for 1930-1931 shows fifteen “service status ratings,” with ten for attendance officers. Salaries rise as the rating progresses. When a teacher has acquired the last “service status rating” listed in the schedule for her division, she has reached the maximum salary rating, and thereafter is paid according to that maximum. These various salary schedules usually contained a provision that the service status rating of the teachers should advance one position each year. Thus, in general, there was an advance of one place in service status rating for each year in the department. There were, however, exceptions to this rule. Thus in 1925-1926, after the salary schedule for that year had been adopted, the board of supervisors made available an additional sum of money to give the teachers an increase in salary. In order to accomplish this result, it being too late, apparently, to revise the salary schedule, the board of education provided that teachers should be advanced more than one place in service status rating for the year 1925-1926. In 1930, as already pointed out, a new schedule was adopted. That schedule contained substantial raises for all high school teachers over the corresponding salaries contained in the schedule for the preceding year. .The board concluded that to give the higher rate, and, at the same "time advance the high school teachers one year in rating, would result in too great an increase. Hence, by resolution, the ratings for high school teachers were “frozen.” .Each teacher in the “frozen” group was to retain the rating of the preceding year. In 1932 the entire schedule was “frozen” and no raises at all allowed for several years thereafter. Under such a system the amount of salary received by each teacher depends on seniority, until the maximum has been reached. Another problem should be generally mentioned. When a teacher first enters the department it is necessary for the board to determine whether she is to be entitled to any credit for experience, either teaching or non-teaching, gained outside the San Francisco School Department. The board determined to give credit for outside experience. To this end, the board on August 11, 1925, adopted a series of rules entitled “Credit for Teaching Experience Elsewhere and in Other Classes of Schools.” These rules purported to state what credit would be allowed not only for outside teaching experience, but also for outside “vocational experience in industry and commerce.” These rules remained in effect until May of 1930, when they were modified in certain respects, and then in February of 1932 the board changed its entire policy on this subject. At that time the board abolished the giving of credit for salary purposes for outside experience, and thereafter commenced all new teachers on the first year-of the salary schedule. • Under the rules adopted in 1925 the applicant for a position would submit to an employee of the board her credentials, including a detailed reference to her outside experience. In January, 1926, there was created a department of personnel whose duty it was to make the preliminary survey. The department of personnel did not always rigidly apply the 1925 rules. Moreover, many applicants had had experience of a type not covered by the rules. The department would calculate a rating for the applicant. This recommendation would be submitted to the personnel committee of the board, composed of three members of the board. This committee would then transmit the recommendation to the full board. The board would then by formal resolution approve, reject or modify this rating, and would provide for the hiring of the teacher at the rating.so fixed. In the various cases here involved there are seventy-five teachers (hereafter discussed in detail under the “non-uniformity” cases) whose ratings were thus fixed by formal resolution- in the years 1925 through 1931, and who strenuously object to being re-rated ab initio in 1932. When the board determined to its satisfaction from Owens-by’s report that a particular teacher had been originally, due to some error, improperly rated and therefore improperly compensated at a rate of salary higher than that to which she was entitled, it sent, prior to the commencement of the school year 1932-1933, a letter to each teacher. This letter informed her that for certain specified years she had drawn salary in excess of the uniform schedule of salary rates fixed by the board for other teachers of the same experience and classification. She was then informed that since July 1, 1930, she had been overrated and the amount of excess salary alleged to have been received was specified. She was told that she had the option of reimbursing the department for the overpayment either by an immediate lump sum payment, or in monthly payments to be deducted from her salary from June 30, 1932, to October 31, 1933. The teachers contend that even if they owed the board money for the overpayments, and even if the board could sue them and recover the overpayments, it had no power to exercise the right of self-help by thus deducting sums from their salaries without their consent, at least after the teachers had challenged the validity of the claims by filing these actions. The teachers did not attempt to enjoin the deductions. When these cases went to trial all the deductions had been made and the money impounded by the board. While we have some doubt of the propriety of a governmental agency, after it has determined that an employee owes it money, to deduct all or part of the amount claimed from the employee’s salary after the employee has challenged the validity of the claim, and before the validity has been determined, we have no doubt at all that if the employee does not see fit to take steps to see that the money.is impounded by the court until the validity of the claim is determined, and then it is determined the employee owed the money, he has waived any objections to the method pursued. In the instant case it has been determined that some of these teachers owed the board various sums of money. Before these cases were tried, the board, by the exercise of a form of self-help, deducted the sums owed to it from these teachers’ salaries. If the teachers in fact owed the money they are in no position at this late date to complain of the procedure adopted by the board. The board insists that all of the petitions for mandate in all of the cases must be denied because the teachers did not exhaust their administrative remedies before instituting these proceedings. It is, of course, well settled that available administrative remedies must be exhausted before redress is had to the courts. (Abelleira v. District Court of Appeal, 17 Cal.2d 280 [109 P.2d 942, 132 A.L.R. 715]; Alexander v. State Personnel Bd., 22 Cal.2d 198 [137 P.2d 433].) The board urges that §§ 5.760 and 5.761 of the School Code provide an administrative remedy that should have been utilized before these mandamus proceedings were instituted. Section 5.760 provides that: “Any teacher whose salary is withheld may appeal to the superintendent of public instruction, who shall thereupon require the superintendent of schools to investigate the matter and present the facts thereof to him.” The next section provides that: “The judgment of the superintendent of public instruction shall be final; and upon receiving it the superintendent of schools, if the judgment is in favor of the teacher, shall, in case the trustees refuse to issue an order for said withheld salary, issue his requisition in favor of said teacher.” These sections have no application to these appeals. These cases do not involve disputes over whether warrants of the teachers were being properly withheld. Here the warrants were made out and delivered to the teachers each month, with a deduction from the amount admittedly owed. The dispute is over the right of the board to re-rate in 1932. The superintendent of public instruction has no power to pass on the complicated], questions of law and fact concerning the proper rating of these teachers. The partial salary withholding feature of the case was incidental to this main feature. Under such circumstances there were no administrative remedies available and mandamus was the proper remedy. (See, Dupuy v. Board of Education, 106 Cal.App. 533 [289 P. 689]; Williams v. Bagnelle, 138 Cal. 699 [72 P. 408].) In their closing brief the teachers argue at some length that whatever right the board may have had to deduct for the overpayments during 1930-1932, it at no time notified the teachers, prior to July 1, 1932, that their compensation for the year 1932-1933 would be pursuant to the reduced rating. It is urged that the notices sent to them in May and June, 1932, merely notified them of their reduced ratings and of the amount of the excess salary received by them prior to June 1, 1932. It is also urged that the re-rating resolution itself did not purport to re-rate for the future. No useful purpose would be served by setting forth the form of letter and the resolution in this opinion. It is true that the letter does not expressly state what the teacher's rating for 1932-1933 will be. But the clear and inevitable implication of the letter, and of the resolution, was that future ratings would be based on the ratings as reduced. Thus the letter to Miss Cushman, which is typical, informs her that she should have been rated 11th year for 1931-1932, but that she had been erroneously rated 12th year. It is true that in her case the court held that the board was without legal right to reduce her rating and salary retroactively for 1931-1932 and that she should be paid on 12th year rating for that year. But the letter clearly indicated the board’s intent that she should be reduced in rating for the future. To anyone familiar with the salary schedule of the San Francisco School Department and familiar with the method of rating teachers, as all the teachers here involved were, the letter could have no other meaning. The Clerical or Mechanical Error Cases In general. As already noted, the trial court held, as to the group of cases where the error in rating was mechanical or clerical, that the board was legally justified in re-rating retroactively and prospectively—that is, that the board could collect the overpayments for the two-year period 1930-1932, and was justified in lowering the ratings of these teachers for the future. There are several categories within this large group and some teachers appear in more than one category. These main categories will be separately considered. The “split year” cases. The trial court correctly placed 47 teachers in this category. Their names and the facts relating to each of their cases are set forth fully in the findings and need not be set forth herein. These cases arose in connection with the granting of the so-called “big raise” in the school year 1925-1926. As already pointed out, the salary schedule for this school year was adopted before the money for the raise of at least $360 per year for each teacher was made available. For this reason a salary schedule without providing for the $360 raise was adopted. But, contingent upon money being made available for the “big raise” the schedule provided as follows: “Under the provisions of this Salary Schedule and of the rules governing the placing of teachers now in service upon the new Schedules, all full-time teachers, all principals, supervisors and assistant supervisors in the day schools will receive during the next school year (1925-1926) an increase of not less than Three Hundred and Sixty Dollars above that which they received during the school year 1924-1925, apart from small odd amounts added or subtracted in order to fit the teachers’ salaries exactly into the new schedule.” This raise was accomplished through placing teachers in a higher rating of the 1925-1926 salary schedule than they would have received with only the usual one year advance of rating. The salary schedule contained a section indicating where on the old schedule (1924-1925) were to be placed the various salary brackets of the 1925-1926 schedule. For example, an elementary teacher who had been receiving a salary of $1400 for the year 1924-1925, the lowest or first service status rating, was to receive $1824 for 1925-1926. In order to arrive at this figure, the schedule adopted a most complicated procedure. As to some of the teachers, it provided that they should be paid on a “split year” basis. For example, the schedule provided that a teacher who was on first year rating for 1924-1925, instead of being placed on second rating for the next school year, was to be jumped and placed on the 5th year rating for the first half of the school year 1925-1926, and on the 6th year rating for the second half. The salary for the 5th year rating on the 1925-1926 salary schedule was $1776, that for the 6th year rating, $1872. One-half of $1776 plus one-half of $1872 is $1824. This feature of paying for one-half of the year according to the 5th rating, and one-half according to the 6th year salary was designated the “split year” rating. On the other hand, a teacher who had 2nd rating in 1924-1925 and received a salary of $1450 that year was advanced to the 6th rating on the 1925-1926 salary schedule, which carried a salary of $1872. Thus the schedule continued up through the various salary ratings. Some ratings were advanced without this “split year” method and others with it. This made the salary schedule most complicated, but the board’s schedule expressly provided for this “split year” system as to certain of the salary brackets and not as to others. No complaint is here made of the board having adopted this procedure. The error which Mr. Owens-by found was in the continuance of the “split year” rating beyond the year 1925-1926. In Mr.' Owensby’s analysis of the 1925-1926 salary schedule, which was adopted as the schedule for the succeeding years until the year 1930-1931, the teacher with “split year” rating 5y2 for 1925-1926 (one-half of year at 5th year rating, second half at 6th) should for the year commencing July 1, 1926 (1926-1927) have been placed on straight 6th year rating and have continued at that rating until the year 1927-1928, when she would have gone on 7th rating for the year commencing July 1, 1927. Instead, for 1926-1927 she was given 6y2 “split year” rating, on 6th the first half of the year and on 7th from January, 1927, to June 30, 1927. This continued, that is, advancement on such plan, until the school year 1930-1931. A new schedule was adopted for that year. At that time the board’s paymaster or superintendent of schools, or both, determined that the “split year” system should be then terminated. To accomplish that object elementary teachers on the “split year” rating were placed on the next even rating plus one, commencing with July 1, 1930. That is, the general rule for elementary teachers that year was that they advanced a year in rating. But if a teacher had 9% year rating for 1929-1930, she was, at the commencement of the school year 1930-1931, given full 11th rating. In Mr. Owensby’s view, and that of the trial court, the continuance of this “split year” system beyond the school year 1925-1926 was contrary to the provisions of the board’s salary schedule for the year 1925-1926, readopted for succeeding years. If a teacher with 5y2. rating during 1925-1926 had for the year 1926-1927 been given 6th rating and thereafter advanced one rating a year, she would for the year 1930-1931 have had 10th rating, instead of 11th. This additional one-half year in rating given by the paymaster in 1930 did not only apply to elementary teachers. As already pointed out, the new salary schedule adopted in that year “froze” high school teachers. They were not given the usual one year advance in rating for that school year. This was because the 1930-1931 schedule was higher than the old schedule and it was felt that the increase in pay would be too large if the teachers got an advance in rating under the higher schedule. But for “split year” teachers in the high schools an advance was in effect given. That is a teacher on 9y2 “split” rating for 1929-1930 was placed on 10th rating. If, for 1926-1927, she had been placed on 6th rating instead of 6y2, as should have been done, she would have found herself for 1930-1931 with 9th rating, rather than 10th. The theory of the board in 1932 was that this “split year” system was continued beyond the year 1925-1926 contrary to provisions of the board’s salary schedule for 1925-1926, readopted for the years up to 1930-1931. In the board’s view, its employees (either the paymaster or the paymaster acting under the direction of the superintendent of schools), acting under a misunderstanding of the board’s direction as contained in the schedule and contrary thereto, continued the “split year” system, thereby giving certain teachers a higher rating than they would have had if the board’s direction contained in the schedule had been followed. The trial court found, in accordance with the board’s interpretation of the salary schedule of 1925-1926 that under that schedule, insofar as it provided as to certain groups for the “split year” method of payment for that school year, such method of payment should have terminated with the school year commencing July 1, 1926; that at that time a teacher who was paid, for example, on the “split year” basis for 1925-1926 one-half on fifth year and one-half on sixth, should have been placed on 6th year rating commencing July 1, 1926, instead of 6% year as was done; that “at no time has the said Department ever adopted or maintained a salary schedule based on semi-annual or split year rates and that when (after said $360.00 increase had been effected) said teachers were advanced from year to year, commencing with the school year 1926-1927, at such semi-annual or ‘split year’ ratings, they were so advanced in violation of said resolution of June 16, 1925, and as an unwarranted continuation of the plan for effecting said $360.00 increase, and that such advances and increases were made by reason of clerical error, inadvertence and mistake on the part of said Department and its employees” (Finding No. 61, Cl. Tr. p. 198); that by reason of these errors occurring in 1926 and in 1930 these teachers erroneously received a full year’s increase in rating; that “none of said advances was made in the exercise of discretion or judgment in the rating of said teachers or any of them . . .■ that in charging said teachers, in 1932, with excessive payments which they had received during the two year period next immediately preceding the time when said charges were made, namely, for the difference between what they received on the erroneous semi-annual or split year basis and what they should have received on the yearly basis shown on said schedule [and in re-rating these teachers prospectively since July 1, 1932] said Board was within its rights, and all such charges were legally and properly made; the Court finds that said overpayments were made to said teachers by and through mistake and clerical error and that all thereof were properly collectible back and were properly and legally collected, and that none of said teachers is entitled to collect back from the defendants any part thereof, or entitled to the mandate of this Court ordering any restoration or change in status.” (Finding No. 18, Cl. Tr. p. 207.) In considering the propriety of the trial court’s ruling there are really two questions involved. The first problem is one of interpretation—that is, should the “split year” have been continued after July 1, 1926 ? The second problem involves a question of law, that is, assuming an error was committed by the employees of the board, could the board in 1932 lawfully recover back the amount overpaid during the period within the statute of limitations? On the first question the teachers contend that there was no misinterpretation of the salary schedule, and that what was done was in accordance with the schedule. That the trial court properly construed the 1925-1926 schedule, which was readopted each year until 1930, is not open to reasonable doubt. In addition to the provision above quoted from the 1925-1926 salary schedule, there was another provision which read: “The adjustments in salary of the teachers now in service to be made at the middle of next session, in order to give teachers proper amount of salary, shall continue in effect until the adjustment is made for August 1st, 1927.” (This date, was, on July 22, 1925, changed to read “July 1st, 1927.”) The salary schedule was adopted in May of 1925. The board in 1932, and the trial court, interpreted the reference to “the middle of next session” as referring to the middle of the 1925-1926 school year, when certain teachers were to be paid for the last half year at a higher rating than for the first half. In their analysis the above provision means that the salary paid for the last half of 1925-1926, was to continue as the salary for 1926-1927, that is until July 1, 1927, in all cases where there had been a middle session adjustment in the year 1925-1926. This appears to be the plain purport of the provision. The teachers, while not seriously contending that the quoted paragraph standing alone should not be so interpreted, seek to qualify the quoted paragraph by an earlier provision in the schedule which reads as follows : ‘ Increases in salary on account of years of service in the San Francisco School Department will be made once annually; effect August 1 [later changed to July 1, as August 1 is an obvious error] each year. ’ ’ The teachers contend that any teacher on a “split year” basis for the school year 1925-1926, for example fifth year rating for the first half of the year and sixth for the second half, was to be rated one full year advance or 6y2 for the school year 1926-1927. The obvious error in this construction is that the “middle of next session” paragraph above quoted is a particular provision applying to those with a “split year” rating, which controls the general provision for annual advancement in rating. The “annual” provision, relied upon by the teachers, obviously applied to those not on a “split year” basis, and applied to the “split year” teachers after July 1, 1927. Once it is determined that the rating these teachers enjoyed in 1932 was the result of an error or mistake, the question next presented is whether the board could then recover the overpayments for the period within the statute of limitations. The trial judge fully discussed this problem in his first opinion. We are satisfied that his discussion adequately disposes of this phase of the problem. We therefore adopt as a portion of this opinion the following portions of the opinion of the trial court: “In my opinion there is no doubt as to the Board’s right to sue the teachers, and therefore none as to its right to deduct from money admittedly owing to them. The legal doctrine upon which the Board based its action in charging back the overpayments, and now justifies that action is that of mistake. The law recognizes and deals with two kinds of mistake,—that of law and that of fact. As a general rule mistake of law is of no legal consequence, just as ignorance of the law is no excuse. Mistake of fact, however, as a general rule furnishes a good ground for relief. Moreover, the mistake need not be mutual, or known to or shared by the party receiving the money. Money paid under a mistake of fact may be recovered back, however negligent the party paying may have been, in making the mistake, unless the payment has caused such a change in the position of the other party that it would be unjust to require him to "refund. (National Bank of California v. Miner, 167 Cal. 532 [140 P. 27].) “Now in these cases it is a close question whether the errors claimed by the Board to have been made by persons employed by the department, whereby the teachers were paid more than they were entitled to (according to the Board) were mistakes of fact or mistakes of law. As the various cases are discussed herein this question will be dealt with. Preliminarily, however, it is sufficient to point out that, generally speaking, where money is paid out by mistake by the state or an agency of government (whether by mistake of fact or mistake of law) it can be recovered back in many instances where, if paid out by an individual or by a private corporation it could not be. “The reason for this, and the theory underlying it, is that the funds paid out are public funds,—trust funds,— and not the property of an individual who can deal with them as he pleases. “Take as an illustration a case where the paymaster of the department erred in the interpretation of a section of the School Code or other legal enactment and because of such erroneous interpretation paid a teacher more than under the law rightly interpreted was coming to her. This would be a mistake of law. “A comparatively recent case in Massachusetts clearly illustrates the rule. (Norfolk County v. Cook, 211 Mass. 390 [97 N.E. 778, Ann.Cas. 1913B 650].) Cook was clerk of the County Court of Norfolk County. The county seat was at Dedham. Cook lived at Weymouth, and journeyed each day from there to the courthouse and back. There was a law allowing clerks necessary travelling expenses, and Cook claimed the expenses of his daily trips and the County Commissioners allowed them. ‘It seems’ says the court, ‘to have been supposed by all parties that the statute authorized the payment of these bills. There is no question of their good faith.’ Here was a plain mistake of law. Cook and the County "Commissioners simply misconstrued the law. Later it was held that "the statute did not authorize the- payments, whereupon the county demanded repayment by Cook, which he refused, and the County sued. The court in that case held that ‘The county treasurer had no authority to pay, and the defendant ho right to receivé this money.’ “The following excerpt from the decision should be read with care: “ ‘His next contention is that the county commissioners as a court adjudicated that the money was due him, and that such adjudication is conclusive upon the county. But this is not tenable. So far as they acted within the statute they were by its plain language acting simply as auditors, and so far as they were acting outside the statute they were acting outside their jurisdiction.’. “And the following should also be noted well for it points out in exceptionally clear and unambiguous language the reason for the exception,—the reason that is to say, why a governmental agency can sue and recover back money paid by mistake (despite the fact that it is not by mistake of fact) where an individual cannot do so. “ ‘As the last ground of defense the defendant invokes for his protection the rule that money voluntarily paid under no mistake as to the facts cannot be recovered back. He takes the position that even if the transfer of the money from the treasury of the county to his pocket was illegal, and even if he neither then nor since has had any equitable right to it, still he will invoke this technical rule of law to keep the money if he can. Without stopping to comment upon the ethical aspects of such a defense we proceed to consider its legal aspects. “ ‘The rule is of very general application between individuals. An individual is dealing with his own money. If, to avoid trouble facing him in the shape of a lawsuit or in any other form, he with full knowledge of the facts and not under compulsion but voluntarily pays out money, he has waived his right to contest the validity of the claim. He is dealing with his own money and as a principal. He can do as he chooses with it and is answerable to no one. But public officers are dealing with money which is not their own and over which their powers are subject to well known limitations. They can pay when the law requires or permits, and they cannot pay when it forbids. So far as they act within their powers the public, whose agents they are, must abide the consequences. But when they act beyond their powers they do not bind their principals. The payment of this money in this case was not the act of the • county, but simply the unauthorized act of a public officer. It was not the voluntary payment of money by the owner, but- by one who Had no beneficial interest in it and who was not authorized by the principal to make the payment. Manifestly one of the chief conditions for the application of the rule is wanting. To such a condition of things the rule does not apply; and such is the great weight of authority.’ (Citing cases.) “See also the annotation at pages 651-653. “A leading case on the same subject is State of Iowa v. Young, 134 Iowa 505 [110 N.W. 292, 13 Ann.Cas. 345]; where the subject is fully discussed and numerous cases cited both in the decision and in the annotation following it. It comes to the same conclusion as the Massachusetts case just cited, and arrives at that conclusion by the same process of reasoning. “See also Jones County v. Arnold, 134 Iowa 580 [111 N.W. 973], and County of Pocahontas v. Katz-Craig Contracting Co., 181 Iowa 1313, 1323 [165 N.W. 422]. “The trust fund rule was applied in this state in the case of City of Petaluma v. Hickey, 90 Cal.App. 616 [266 P. 613]. There the City of Petaluma had paid out upwards of $3000 and sued to get it back. The money had been paid out under circumstances which made it neither a mistake of fact nor of law, but it was held that the money was a trust fund and that the person to whom it had been paid had become an involuntary trustee. The City could not recover, however, for the single reason that it had not brought suit in time,— its claim on the trust theory being barred by the statute of limitations. “The case of Puterbaugh v. Wadham, 162 Cal. 611, 620 [123 P. 804], tacitly recognizes and applies the same rule, holding past overpayments to be deductible from salary.” (Opinion quoted in entirety Res. Br. pp. 69-131; part here quoted Res. Br. pp. 76-81.) In addition to the cases cited above, the following cases hold that money paid out by a governmental agency under either mistake of fact or law may be recovered from the payee: Foster v. Pension Board, 23 Cal.App.2d 550 [73 P.2d 631]; City of Duluth v. McDonnell, 61 Minn. 288 [63 N.W. 727]; Chrysler Light & Power Co. v. City of Belfield, 58 N.D. 33 [224 N.W. 871, 63 A.L.R. 1337]; Independent School Dist. No. 6 v. Mittry, 39 Idaho 282 [226 P. 1076]; Inhabitants of City of Biddleford v. Benoit, 128 Me. 240 [147 A. 151]; United States v. Barlow, 132 U.S. 271 [10 S.Ct. 77, 33 L.Ed. 346]; Wisconsin Central R. Co. v. United States, 164 U.S. 190 [17 S.Ct. 45, 41 L.Ed. 399]; Haralson County v. Golden, 104 Ga. 19 [30 S.E. 380]. It should be added that the good faith of the payee iu no way affects the applicability of the above rules. (Smith v. Rubel, 140 Ore. 422 [13 P.2d 1078, 87 A.L.R. 644]; Grand Lodge, A.O.U.W. of Minnesota v. Towne, 136 Minn. 72 [161 N.W. 403, L.R.A. 1917E 344].) The teachers, as to this and all other cases of error, urge that the ratings having been once given, although based on error, are final, and, that in any event, the board is estopped from challenging, or that the board has ratified, the ratings. It should be noted that we are not here dealing with ratings given by the board after full examination of the facts by the board. That problem will be discussed hereafter. We are here dealing with errors of employees of the board in applying the will of the board as disclosed in its resolutions or in the salary schedule. The so-called “mechanical error” cases were the result of employees of the board erroneously interpreting the salary schedule passed by the board or in interpreting some resolution of the board. Certainly, it cannot be urged successfully that the employees of the board in rating teachers and paying their salary and in interpreting the resolutions of the board acted in a judicial or quasi judicial capacity so that their determinations would become res judicata. Yet this is the necessary import of the argument of the teachers on this point. The same fallacy exists in the arguments based on estoppel and ratification. It is urged that, however erroneous the interpretation by the employees of the salary schedule and other resolutions of the board may have been, the board should have known in what manner the paymaster’s department was violating the resolutions. It is also urged that the records of the board were open to the board, and that such records revealed the true situation. The above cited cases establish beyond a doubt that in the absence of unusual circumstances not here present an illegal payment of public funds cannot be ratified nor can recovery be estopped. There is no doubt a modern tendency to invoke estoppels against public authority in exceptional circumstances. (La Societe Francaise v. California Emp. Com., 56 Cal.App.2d 534 [133 P.2d 47]; Times-Mirror Co. v. Superior Court, 3 Cal.2d 309 [44 P.2d 547]; McGee v. City of Los Angeles, 6 Cal.2d 390 [5 P.2d 925]; City of Los Angeles v. County of Los Angeles, 9 Cal.2d 624 [72 P.2d 138, 113 A.L.R. 370].) But these cases all involved most unusual sets of facts. There is no doubt that the general rule is that estoppels will not be invoked against the government or its agencies except in rare and unusual circumstances. (See cases collected 19 Am.Jur. p. 818, § 166.) No unusual circumstances are here presented. It is a simple ease of employees of the board erroneously interpreting the will of the board and illegally paying out money to those not lawfully entitled. We conclude that in this, as well as in all the other mechanical error cases, the board upon discovering the error, lawfully could recover the illegal payments for the period not barred by the statute of limitations, and, of course, was required to restore the teachers involved to their proper ratings. The “frozen year” cases. As to the group of teachers here involved the trial court, as in the “split year” cases, held there was mechanical error, and for that reason the teachers were without right to recover the deductions, or to be re-rated prospectively. The trial court found, as to this group of cases, that the employees of the board, in applying and interpreting the salary schedule, acted contrary to the will of the board as disclosed by the resolutions of the board. As has already been pointed out, the salary schedule for 1930-1931 gave a substantial raise in salary for each of the ratings relating to senior and junior high schools, but gave no such similar raise to elementary teachers. The board determined that to give the high school teachers both the raise and the usual one year advance in rating would result in giving those teachers more of an increase than the board intended. To prevent this result the board determined to “freeze” the status of the high school teachers for one year —that is, to keep their service status ratings for 1930-1931 identical with those existing in 1929-1930. Inasmuch as the elementary teachers did not receive a raise, their service status ratings were not frozen. The “freezing” resolution was adopted on May 21, 1930, and reads as follows: “All senior high school teachers [an identical resolution was adopted relating to Junior High School teachers] with less than twelve years service shall be placed beginning July, 1930, on the year of the new schedule corresponding to their service status as of the date of the adoption of this schedule, and shall advance thereon according to the requirements and effective dates set forth, except that in no event shall a teacher now in the service suffer a reduction of salary by virtue of the adoption of the new schedule.” Many of the cases now under discussion involve elementary teachers who were transferred to the junior or senior high schools effective July 1, 1930. If those teachers had remained in the elementary division they would have advanced a year in rating. The board’s employees advanced them one place in rating notwithstanding the transfer to high school. The result was that a teacher with two years’ teaching experience in the junior high remained on second rating for 1930-1931, but the elementary teacher transferred to the junior high with two years’ elementary experience received third rating on the junior high schedule, getting a higher salary than the teacher whose entire experience had been in the junior high. The re-rating of 1932 placed such transfers on the same basis as those who were junior high teachers and were “frozen.” Other elementary teachers involved in this group were transferred effective as of July 1, 1931. Salary ratings did not freeze for the year 1931-1932. But it is perfectly obvious that if an elementary teacher was, for example, advanced from second to third rating for 1930-1931 (which was perfectly proper) and then, when she was transferred to the high school division commencing July 1, 1931, if she were to be advanced to fourth rating, she would be one year ahead of the junior or senior high school teacher of similar years experience all of whose experience had been in the high school. That is exactly what the employees of the board did. The same situation existed as to new entrants in the department. Outside teachers were given credit for each year of their outside teaching experience, less one. As a result such new entrant was placed on the salary schedule one year ahead of high school teachers in the San Francisco department with equal experience whose entire teaching had been done in the San Francisco high schools. A somewhat similar situation existed as to attendance officers. Before 1930-1931 their separate salary schedule was midway between elementary and junior high. The salary schedule of 1930-1931 placed them on the junior high schedule.' The board’s employees did not “freeze” their ratings, but permitted an advance of one place. Thus if an attendancé officer had second rating, she was advanced to third rating and given the same salary as third rating junior high teachers. Thus an attendance officer who, for 1929-1930 had second rating and received less than a junior high teacher with second rating, in 1930-1931 was paid on the basis of third junior high rating, receiving more than the junior high teacher with equal experience. The re-rating of 1932 reduced these several groups one place in rating so as to give them one frozen year, and provided for the recovery of the overpayments. The trial court approved these actions of the board, holding that all of these teachers should have been frozen in the schedule for one year. That this determination was correct seems obvious. When the purpose of the freezing resolution is considered, it seems clear that these groups were intended to be included in the frozen group. Such conclusion is predicated upon the scheme of the 1930-1931 schedule as a whole, rather than upon any particular provision of the schedule. For the reasons and upon the authorities discussed under the “split year” cases this portion of the judgment should be affirmed. The vice-principal cases. This category includes four vice-principals. The problems here involved also grow out of the 1930-1931 salary schedule. Under that schedule vice-principals were given a rating on the teacher’s service status rating schedule, and in addition to the teacher’s salary for that rating received a flat sum of $300 per year in addition, except for Class B, elementary schools, where $240 per year additional was received. The salary schedule for 1930-1931 was adopted by the board on May 21, 1930. In reference to vice-principals the schedule provided,: “All vice principals, except those of Class B, elementary schools, who shall not have had at the time of the adoption of this schedule the respective service status as listed above [14th and 15th year ratings], shall receive the salary, on the new schedule for their respective teacher groups, of a year, three years in advance for their 1929-1930 service status plus $300 per annum.” A similar provision applied to Class B, elementary' school vice-principals, except that their flat raise was to be $240. It will be noted that under this schedule, vice-principals “at the time of the adoption of this schedule” who had not already reached maximum rating, were to receive for 1930-1931 a three-year jump in rating plus an additional sum of either $300 or $240 per year. The four vice-principals here involved were not vice-principals “at the time of the adoption of this schedule.” They were appointed vice-principals after May 21, 1930, either for the school year 1930-1931, or for the school year 1931-1932. The paymaster nevertheless gave these four vice-principals a three-year advance in rating upon their appointment, in addition to the flat sum increase to which they were undoubtedly entitled. This was clearly an erroneous application of the schedule. The board had determined that the extra raise of a three-year jump in rating should be limited to those in service on May 21, 1930. That classification was based on the theory that most of the vice-principals already in service had years of experience in their positions and were entitled to the extra big raise of three jumps in rating. Acting well within its powers, the board determined that newly appointed and therefore inexperienced vice-principals were not entitled to this consideration. The paymaster clearly acted in violation of the board’s mandate. The rating as to the group here involved was therefore erroneous. The board, for reasons fully discussed in connection with the “split year” cases, properly collected back the overpayments, and properly placed these persons on their proper ratings. The judgment should be affirmed as to them. Gases where the teachers admit error. In the cases of Nellie Foley, Frances Murphy, Edna Jiminez Herrington, Dorothy Reilly and Ruth Peabody, counsel for the teachers admits that a purely mechanical error was made in their ratings by the employees of the board. To this group should be added Emma Betts, .not mentioned in the brief of the teachers. As to these teachers the trial court found that “for some unexplained reason or for no reason at all,” or “through some clerical error and mistake, which is wholly unexplained,” or “for some unexplained reason and because of clerical error,” or because of “error and inadvertence,” the paymaster gave these teachers a higher rating than they were entitled to under the resolutions of the board. For example, teacher Nellie Foley was given fifth year rating by resolution of the board in 1926. The paymaster erroneously placed her in the seventh year. The other five cases are similar. These cases furnish the clearest examples in the record of purely mechanical errors by which the teachers involved were overrated. The board properly recovered the overpayments made to these teachers, and properly re-rated them in 1932 by placing them on their proper rating. The judgment as to them should be affirmed. Miscellaneous cases. The teachers list five persons under this heading. As contended by the board, and as found by the trial court, all five of these cases fall within one or more of the categories heretofore or hereafter discussed. Perry Kittredge for the school year 1924-1925 was entitled to a rating calling for an $1800 salary. He was paid at that rating until February, 1925, when for some unexplained reason he was raised to the next rating by the paymaster at $1900 per year. There is no evidence of any resolution warranting the raise in rating, and no evidence of any practice or custom of thus raising a teacher in mid-year. This rating was clearly the result of some mechanical and wholly unexplained error by the paymaster’s department. The board admits that Charlotte Morton should be in the “non-uniformity” group, hereafter discussed. The rulings hereafter made as to that group will apply to this teacher. Mary Rossi falls both within the “frozen” year eases, heretofore discussed, and the “nine months rule” cases, hereafter discussed. The respective rulings there made as to each group shall apply to this teacher. The eases of Kathryn Coles and Eloísa Courtright fall within the “nine months rule” and the “split year” categories, and the respective rulings made as to those categories shall apply to these two teachers. Conclusion as to mechanical error cases. The above constitute the main groups found by the trial court to fall within the mechanical error category. We are convinced that as to all of these cases (those mentioned above as well as those not specifically mentioned but set forth in the findings of the trial court) the trial court correctly determined that overpayments based on error were properly collectible for the period within the statute of limitations, and that the board acted well within its powers in placing these teachers prospectively in the rating they would have been in had the error not occurred. “Nine months rule” cases. The board contends that the teachers falling within this group should also be classified with the mechanical error cases. The solution of the problem here involved depends upon the proper interpretation to be given to a rule adopted by the board. If the employees of the board correctly interpreted this rule the ratings given these teachers were proper, and no error was committed. On the other hand, if the employees of the board misinterpreted the rule, then an error was committed and the cases should follow the same course as the other mechanical error eases. The trial court found that the rule in question had no application to the teachers in this group. It therefore found that the ratings given these teachers by the employees of the board were correct—in other words, that no error had been committed.. Accordingly, the trial court ruled that no over-payments had been made as to these teachers, that the board had no legal right to deduct any sum from their salaries, and that these teachers were entitled to a refund for all sums so deducted. The board appeals from this portion of the judgment. The trial court held, however, that the board had power to classify this group, for salary purposes, prospectively, and that it had properly re-rated these teachers in 1932. The teachers appeal from this portion of the judgment. According to the findings there are twenty-five teachers in this group. They are all teachers who were in the department and who taught for part of a year and then took leaves of absence. The portion of the year that these teachers taught was less than nine months. The board had adopted certain rules on August 11,1925, to guide it and its employees in the matters covered by the rules. These rules read as follows : “Credit for Teaching Experience Elsewhere and in Other Classes of Schools. ‘ ‘ Credit for teaching experience elsewhere and for teaching experience in other classes of schools may be graded for salary adjustment purposes as follow: “(A) Teachers with less than three years of.successful experience in teaching elsewhere, .appointed to positions, as teachers in the San Francisco Public • Schools, shall receive an annual salary provided for the first year of the Salary Schedule. Teachers with three years’ experience shall receive the salary provided in the second year of the schedule; with four years’ experience in the third year of the schedule; with five years’ experience in the fourth year of the schedule; with six years’ experience in the fifth year of the schedule; with seven years ’ experience in the sixth year of the schedule; with eight years of experience in the seventh year of the schedule; with nine years’ experience in the eighth year; with ten years’ experience in the ninth year; with eleven or more years of experience in the tenth year. “(B) Elementary school teachers in the San Francisco School Department when- assigned to teaching positions in the high schools shall receive credit for salary adjustment year for year for all teaching experience in the San Francisco Schools, but not to exceed the tenth year of the high school salary schedule. High schools as here used include the junior, part-time and high schools. “(0) Teachers in the junior high school when assigned to the part-time school or the high school, and teachers in the part-time high school or assignéd to the high school, shall receive credit year for year for teaching experience in the junior or in the part-time high school. “(D) Credit on the basis of two years for one may be given for vocational experience in industry or in commerce to teachers of industrial or commercial branches when such industrial or commercial experience is directly related to the proper preparation for teaching in the respective industrial or commercial branches, provided that the total of such credit shall not entitle the teacher to a salary position higher than the tenth year of the schedule. “(E) Evening school teachers, when assigned to duties as teachers in the day schools, shall be entitled to credit on a basis of two years’ evening school teaching for one year on the salary schedule for day schools. “(F) Not more than one year of credit shall be given for teaching experience during one year, and no credit shall be given for a term of service of less than nine months during one year. “(G) Teachers asking for salary adjustments on account of teaching experience elsewhere must file with the Superintendent satisfactory evidence of such experience in years and in months, and the places where such experience was obtained. ’ ’ The precise question presented is whether Rule F, supra, applied to teachers in the department who took leaves of absence, or whether it only applied to new entrants into the department, in rating their outside experience. The paymaster interpreted the.rule to apply only to new entrants. Accordingly, as to the teachers on leave, when they returned, the paymaster advanced them one year in rating although they had not taught a full nine months in the year in which the leave was taken. The trial court agreed with this interpretation, holding that “Rule F” had no application to teachers on leave. It should be pointed out that all teachers similarly situated were so treated by the paymaster. We agree with the interpretation of this rule given it by the trial court. In his second opinion Judge Goodell discussed this problem at some length. We agree with his analysis. We therefore adopt as part of the opinion of this court the following portions of the trial court’s second opinion: “In seeking the true intent and meaning of Rule F it is certainly proper to analyze the six rules in whose company it is found. “A reading of Rule A shows that it can apply only to new teachers entering the San Francisco Department. In a word, it says that three years teaching experience here are as good as four elsewhere. This rule was referred to hundreds of times during the trial of these cases. “Rule B, on the other hand, clearly refers exclusively to teachers already settled in the San Francisco Department (elementary) who are ‘assigned’ to either junior high, part-time high or high school proper. “Rule C, following the principle announ