Opinion
MOSK, J.
An important provision of our statutory landlord-tenant law provides that within three weeks after the termination of tenancy a landlord must return the security deposit paid by a former tenant and provide a written accounting of any portion retained as compensation for unpaid rent, repairs, and cleaning. (Civ. Code, § 1950.5, subd. (f).)1 We granted review to determine whether a landlord who in good faith fails to comply with the requirements of this statute may nevertheless recover damages for unpaid rent, repairs, and cleaning in a subsequent judicial proceeding. We also consider whether the trial court abused its discretion by not requiring defendants to disgorge all security deposits received from the members of the plaintiff class and to pay this money into a fund. Finally, we consider whether the court abused its discretion by limiting the award of attorney fees and costs to 25 percent of the total class recovery.
We conclude that a good faith failure to comply with section 1950.5, subdivision (f), does not bar a landlord from recovering damages for unpaid [742]*742rent, repairs, and cleaning, and we agree with the Court of Appeal to the extent that it so held. We disagree with its view of the remaining issues, however, and hence reverse its judgment to permit the trial court to reconsider its choice of remedy and limitation on attorney fees.
Facts
Defendants own or operate between 1,200 and 1,500 residential rental units in the Santa Barbara area. During the period relevant to this case, April 27, 1978, to April 27, 1981, it was defendants’ practice to charge tenants an increased rental fee for the first 31 days of tenancy, but to charge a reduced fee for all subsequent months.2 Defendants never returned this fee in whole or in part; rather, they simply retained it as part of the rental payment for the first month. Approximately 10,000 tenants paid such fees during the relevant period, and the aggregate amount of such fees was approximately $1 million.
Plaintiffs, a class of former tenants, sued for a refund of the amount by which the rent they had paid for the first 31 days of their tenancy exceeded the amount they paid in each of the following months. The court entered summary judgment in favor of defendants on the ground that the increased rent paid during the first month was in fact rent and not a security deposit within the meaning of section 1950.5, subdivision (b),3 and therefore plaintiffs were not entitled to a refund. In an earlier appeal the Court of Appeal reversed, holding that the character of the payment was a triable issue of fact. (Granberry v. Islay Investments, supra, 161 Cal.App.3d 382.) On remand, the court granted defendants leave to amend their answer to allege they were entitled to set off amounts owed to them for unpaid rent, repair, and cleaning if a jury were to find the increased rental payment was a refundable security deposit.
Plaintiffs subsequently moved for summary judgment on the question whether defendants were entitled to a setoff in view of the fact that they had [743]*743failed to comply with the requirements of section 1950.5, subdivision (f). The court granted the motion. A jury thereafter found that the excess rental payments were security deposits within the meaning of section 1950.5, subdivision (b), but that defendants had not retained them in bad faith. The court ruled that the excess fees must be refunded to the members of the class who made individual claims, but it did not require defendants to disgorge the aggregate amount of the security deposits they wrongfully retained and to pay that money into a fund. The judgment also awarded costs and attorney fees to plaintiffs, but provided that such items would be recovered from the aggregate amount paid by defendants and would not exceed 25 percent of the total amount claimed by the individual members of the class.
In a second appeal the Court of Appeal held (1) the trial court erred in ruling that defendants were not entitled to a setoff, (2) the court did not abuse its discretion in granting refunds only to those class members who came forward to claim them, and (3) it was not an abuse of discretion to limit the award of attorney fees and costs to 25 percent of the total amount paid to the class. Although the Court of Appeal purported to reverse the judgment in its entirety, it in fact impliedly affirmed the judgment as to the second and third of these issues.4
I.
During the three-year period relevant to this litigation, plaintiffs vacated apartments rented from defendants but did not receive a written accounting of the basis for, or the amount of, the security deposits retained or the disposition of these security deposits. Nor did plaintiffs receive a refund of any portion of their security deposits. Accordingly, both the trial court and the Court of Appeal correctly concluded that defendants failed to comply with section 1950.5, subdivision (f). The issue now before us is whether, notwithstanding their good faith lack of compliance, defendants may set off amounts allegedly due for unpaid rent, repairs, and cleaning against money due plaintiffs as a refund of their security deposits. We conclude that defendants may do so.
The English chancery courts allowed setoff to be raised as a defense as early as the 17th century. (Prudential Reinsurance Co. v. Superior Court (1992) 3 Cal.4th 1118, 1124 [14 Cal.Rptr.2d 749, 842 P.2d 48]; 3 Story, Commentaries on Equity Jurisprudence (14th ed. 1918) § 1867, pp. 468-469; [744]*744see also Tigar, Automatic Extinction of Cross-Demands: Compensado From Rome to California (1965) 53 Cal.L.Rev. 224 [tracing the history of setoff to the Roman law concept of compensado].) It was founded on the equitable principle that “either party to a transaction involving mutual debts and credits can strike a balance, holding himself owing or entitled only to the net difference, . . (Kruger v. Wells Fargo Bank (1974) 11 Cal.3d 352, 362 [113 Cal.Rptr. 449, 521 P.2d 441, 65 A.L.R.3d 1266].) Setoff, as it applies to this case, is now codified as section 431.70 of the Code of Civil Procedure, which provides in pertinent part: “Where cross-demands for money have existed between persons at any point in time when neither demand was barred by the statute of limitations, and an action is thereafter commenced by one such person, the other person may assert in the answer the defense of payment in that the two demands are compensated for so far as they equal each other, . . .” The quoted statute, however, does not create a substantive right to raise setoff as a defense to a claim for monetary relief, but merely describes the procedures to be followed in raising this defense. (Kruger v. Wells Fargo Bank, supra, 11 Cal.3d 352, 362; Hauger v. Gates (1954) 42 Cal.2d 752, 755 [269 P.2d 609].) To determine whether setoff is available in this case, we must turn to section 1950.5.
We first consider whether to allow a landlord to raise setoff even though he has failed to comply with the requirements of section 1950.5, subdivision (f), is consistent with the legislative intent underlying that statute. (See Prudential Reinsurance Co. v. Superior Court, supra, 3 Cal.4th 1118, 1125.) “In determining intent, we look first to the words themselves. [Citations.] When the language is clear and unambiguous, there is no need for construction. [Citations.] When the language is susceptible of more than one reasonable interpretation, however, we look to a variety of extrinsic aids, including the ostensible objects to be achieved, the evils to be remedied, the legislative history, public policy, contemporaneous administrative construction, and the statutory scheme of which the statute is a part. [Citations.]” (People v. Woodhead (1987) 43 Cal.3d 1002, 1007-1008 [239 Cal.Rptr. 656, 741 P.2d 154].)
Section 1950.5, subdivision (e), allows a landlord to claim any portion of the security deposit reasonably necessary to compensate for unpaid rent, repairs, and cleaning. Section 1950.5, subdivision (f), provides in pertinent part: “Within three weeks after the tenant has vacated the premises, the landlord shall furnish the tenant ... a copy of an itemized statement indicating the basis for, and the amount of, any security received and the disposition of the security and shall return any remaining portion of the security to the tenant.” From the plain language of the statute we conclude that a landlord (1) must return a tenant’s security deposit within the [745]*745specified period after the termination of the tenancy, (2) may retain all or part of the security deposit as compensation for unpaid rent, repairs, and cleaning, and (3) must provide a written accounting of any amounts retained within the specified period. If, within the specified period, the landlord has not provided the tenant with a written accounting of the portion of the security deposit he plans to retain, the right to retain all or part of the security deposit under section 1950.5, subdivision (f), has not been perfected, and he must return the entire deposit to the tenant, Nevertheless, the mere fact that the landlord has lost the right to take advantage of the summary deduct-and-retain procedure of section 1950.5, subdivision (f), does not lead to the conclusion that he has lost all right to claim damages for unpaid rent, repair, and cleaning, whether through setoff or otherwise. The language of section 1950.5, subdivision (f), offers no clear guidance on this issue. Accordingly, we must look to the legislative history of section 1950.5 to determine the intent of the Legislature on this point. (People v. Woodhead, supra, 43 Cal.3d 1002, 1008.)
In 1970, the Legislature enacted section 1951, the predecessor of section 1950.5. Former section 1951, subdivision (c), provided: “The landlord may claim of such payment or deposit only such amounts as are reasonably necessary to remedy tenant defaults in the payment of rent, to repair damages to the premises caused by the tenant, or to clean such premises upon termination of the tenancy, if the payment or deposit is made for any or all of those specific purposes. Any remaining portion of such payment or deposit shall be returned to the tenant no later than two weeks after termination of his tenancy.” (Stats. 1970, ch. 1317, p. 2453.) Ostensibly, the Legislature enacted section 1951, subdivision (c), to prevent the misuse of security deposits, which one contemporary commentator described as follows: “Theoretically, the security deposits are created to insure against the contingencies of unpaid rents, tenant-inflicted damages, and unclean premises at the termination of the lease. Any claim as to the retention of these funds by the landlord arises only at such time as there has been a breach of the tenant’s obligation and an assessment of damage. However, the security deposit in actuality has evolved into a bonus to be kept by the landlord upon termination of the lease agreement regardless of the damages actually sustained by the landlord. Landlords will retain security deposits after the departure of a tenant secure in the knowledge that a former tenant is severely inhibited from initiating legal action. This restraint is a product of a combination of factors including problems of proof, the relatively small sum of money at issue, the time factor, and the distance now separating the tenant from his former landlord. Where the reimbursement is forthcoming, usually the payments are delayed, the application of the retained amounts unitemized, and the interim retention and use of the funds having been without cost [746]*746to the landlord.” (Jory, The Residential Lease: Some Innovations for Improving the Landlord-Tenant Relationship (1971) 3 U.C. Davis L.Rev. 31, 38-39, fns. omitted; see also Bosshardt, The Rental Security Deposit in California (1971) 22 Hastings L.J. 1373.) In 1972, the Legislature renumbered section 1951 as section 1950.5, but did not change the wording of subdivision (c). Finally, in 1977, the Legislature enacted the version of section 1950.5 in effect during the events of this case (now section 1950.5, subdivision (f)).
From the foregoing history it is apparent that section 1950.5, subdivision (f), was enacted to ensure the speedy return of security deposits on the termination of tenancy and to prevent the improper retention of such deposits. However, like the Court of Appeal, we find no conclusive evidence in the legislative history of section 1950.5 regarding the specific issue we now address—namely, whether a landlord may recover damages for unpaid rent, repair, and cleaning even if he has failed in good faith to avail himself of the summary deduct-and-retain procedure permitted under section 1950.5, subdivision (f).
Defendants note that the original draft of a bill proposed in 1985 would have added language to section 1950.5 specifically denying offsets for landlords that fail to comply with section 1950.5, subdivision (f), but this language was deleted from the bill prior to enactment. They contend that this proves that the Legislature, at least in 1985, intended to allow offsets. In response, plaintiffs note that defendants urged the passage of two bills, one in 1990 and another in 1991, but that these bills also failed. Again like the Court of Appeal, we find these arguments unpersuasive. As we have often observed, “Unpassed bills, as evidences of legislative intent, have little value.” ([Dyna-Med, Inc. v. Fair Employment & Housing Com. (1987) 43 Cal.3d 1379, 1396 [241 Cal.Rptr. 67, 743 P.2d 1323]; accord, Grupe Development Co. v. Superior Court (1993) 4 Cal.4th 911, 922-923 [16 Cal.Rptr.2d 226, 844 P.2d 545].)
Defendants also remind us that we should construe section 1950.5, subdivision (f), in a way that will give effect to section 1950.5 as a whole, leaving no part useless or deprived of meaning. (Gay Law Students Assn. v. Pacific Tel. & Tel. Co. (1979) 24 Cal.3d 458, 478 [156 Cal.Rptr. 14, 595 P.2d 592].) They draw our attention to section 1950.5, subdivision (k), which provides in pertinent part: “The bad faith claim or retention by a landlord ... of the security or any portion thereof, in violation of this section . . . , may subject the landlord ... to statutory damages of up to six hundred dollars ($600), in addition to actual damages. ... In any action under this section, the landlord . . . shall have the burden of proof as to the reasonableness of the [747]*747amounts claimed . . . .”5 According to defendants, this provision is “critical” for two reasons. First, they argue that if the Legislature had intended to bar all claims for damages for unpaid rent, repair, and cleaning other than those made in accordance with section 1950.5, subdivision (f), it would not have been necessary to allocate the burden of proof regarding reasonableness, because the matter would never be litigated. According to defendants, this provision could only have meaning in cases in which the landlord has failed to comply with section 1950.5, subdivision (f), the tenant has sued for a refund, and the landlord seeks setoff. The argument misses the mark: the second sentence of section 1950.5, subdivision (k), would also apply in cases in which the tenant contests the accounting required under section 1950.5, subdivision (f), and sues for a refund of all or part of the amount deducted and retained under that provision.
Second, defendants contend that because the Legislature provided a remedy only for bad faith retention of a security deposit, we can infer it did not intend to impose a penalty for good faith retention. They conclude that landlords like themselves that have retained security deposits in good faith should not be penalized by being barred from raising setoff. This argument is persuasive. “[I]t is well settled that ‘ “Courts will not impose penalties for noncompliance with statutory provisions in addition to those that are provided expressly or by necessary implication.” ’ [Citations.]” (People ex rel. Van de Kamp v. American Art Enterprises, Inc. (1983) 33 Cal.3d 328, 334 [188 Cal.Rptr. 740, 656 P.2d 1170].) Because the Legislature has not expressly stated that landlords that fail to comply with section 1950.5, subdivision (f), in good faith are barred from recovering for unpaid rent, repairs, and cleaning, we find that no such penalty was intended and we will not imply such a penalty.
Plaintiffs vigorously contend this result is inconsistent with principles of equity and with public policy. (See Prudential Reinsurance Co. v. Superior Court, supra, 3 Cal.4th 1118, 1139 [considering principles of equity and public policy in determining whether setoff was available].) They first urge that to allow landlords to raise setoff as a defense would be inconsistent with the equitable principle that an individual should not profit from his own wrong, because landlords may use this defense to keep all or part of the security deposits they retained in violation of section 1950.5, subdivision (f). While we recognize the importance of this equitable principle (see § 3517), and while we do not doubt that this principle may bar setoff on the particular facts of many individual cases, it does not justify an absolute bar to the right to a setoff in all cases.
[748]*748 When enacting, interpreting, or applying a rule of law that regulates the interaction between individual citizens, the lawmaking body should consider carefully before creating absolute and invariable rules. Normally, such laws should be as flexible as the regulated interactions are varied, and they should leave the courts with some discretion to apply them justly given the facts of the case before them. (See Heriot, A Study in the Choice of Form: Statutes of Limitation and the Doctrine of Laches, 1992 B.Y.U. L. Rev. 917, 920 [“In promulgating any kind of law, one of the tasks a lawmaker must perform is to select the best formulation of that law—the one that delegates to the law administrator the level of discretion and authority that is just right.”].) Without some degree of flexibility, harsh and improper results may occur. (See id. at p. 937, fii. omitted [Comparing strict rules, like statutes of limitations, to more flexible standards, like the doctrine of laches, and asserting that as lawmakers move toward more rigid rules, “there is an increasing potential for incorrect judgments—judgments that would not reflect the lawmaker’s preferences had the lawmaker adjudicated the case personally on an all-things-considered basis .... The rigidity of rules creates errors. [¶] . . . [A] rulelike statute of limitations will always be both underinclusive and overinclusive .... [and therefore] [i]t will never be a perfect reflection of its underlying policies.”].) Such flexibility is particularly appropriate when applying equitable doctrines, such as setoff. (See, e.g., Holmberg v. Armbrecht (1946) 327 U.S. 392, 396 [90 L.Ed. 743, 747, 66 S.Ct. 582, 162 A.L.R. 719] [“Equity eschews mechanical rules; it depends on flexibility.”].)
In addition, a landlord that seeks setoff after good faith noncompliance with the procedures described in section 1950.5, subdivision (f), does not “profit from his own wrong,” because he cannot set off any damages he could not have recovered if he had complied with section 1950.5, subdivision (f). Indeed the landlord suffers a great deal if he delays, because he loses the opportunity to take advantage of the summary nonjudicial procedure allowed under that statute, and must instead prove in court by a preponderance of the evidence that he is entitled to damages and that the amount claimed is reasonable. (§ 1950.5, subd. (k).) This burden of proof will become ever more difficult to sustain the longer the landlord delays, because the evidence supporting his claim may be lost with the passage of time.
Second, plaintiffs contend that to allow defendants to raise setoff would violate the equitable principle that an individual may not change his position to the detriment of another. (See § 3512.) They note defendants originally claimed (1) the excess payments were rent, (2) they had never demanded or received security deposits from plaintiffs, and (3) they, not plaintiffs, were to [749]*749bear the cost of unpaid rent, repairs, and cleaning. Only after the excess payments were found to be security deposits did defendants claim they were entitled to a setoff. Plaintiffs argue this change of position worked to their detriment because they did not receive adequate notice of defendants’ claims. However, the original class notice contained the following paragraph: “Defendants contend that any refund you might be entitled to recover must be reduced by the amount of any unpaid rent, costs reasonably necessary to clean and repair damage you caused to the apartment, in excess of ordinary wear and tear, and that such sum could exceed the amount of any refund or damages you might receive.” In light of this notice, plaintiffs’ contentions regarding estoppel and lack of notice are unavailing.
Finally, plaintiffs contend that to allow setoff would be inappropriate in class actions such as this because of numerous practical difficulties. They stress that (1) the class is comprised of approximately 10,000 individuals, many of whom may have moved to other parts of the state or country, (2) defendants have raised between 6,200 and 8,000 claims for setoff, which must be litigated individually, (3) because the security deposits in question are between $100 and $150, a relatively small amount of money, many class members may not appear to oppose defendants’ claims, and (4) if the class members do not appear, defendants will prevail by default on their claims for setoff, and may be unjustly enriched. Given these difficulties, plaintiffs ask us not only to bar defendants from raising setoff, but to reconsider our many earlier decisions holding setoff may be raised when the claims are not liquidated (see, e.g., Erlich v. Superior Court (1965) 63 Cal.2d 551, 555 [47 Cal.Rptr. 473, 407 P.2d 649]; Hauger v. Gates, supra, 42 Cal.2d 752, 755), at least in the context of class actions. We decline to do so for two reasons. First, it may well be possible on remand to shape a remedy that will avoid many of the problems plaintiffs have identified. Second, it is inappropriate to deprive defendants of their substantive rights merely because those rights are inconvenient in light of the litigation posture plaintiffs have chosen. (See City of San Jose v. Superior Court (1974) 12 Cal.3d 447, 462 [115 Cal.Rptr. 797, 525 P.2d 701, 76 A.L.R.3d 1223], fn. omitted [“Class actions are provided only as a means to enforce substantive law. Altering the substantive law to accommodate procedure would be to confuse the means with the ends—to sacrifice the goal for the going.”].)
For the reasons stated, we conclude that a landlord who has failed in good faith to take advantage of the summary nonjudicial deduct-and-retain procedure allowed under section 1950.5, subdivision (f), may recover damages for unpaid rent, repairs and cleaning (§ 1950.5, subd. (e)) in a subsequent judicial proceeding provided that he proves by a preponderance of the evidence that he has suffered such damages and that the amount claimed is [750]*750reasonable (§ 1950.5, subd. (k)).6 The trial court erred in ruling to the contrary, and that court must now hold an evidentiary hearing to determine whether defendants have sustained this burden. Because defendants have raised their claims through the equitable defense of setoff, the trial court must also determine whether defendants’ claims are barred by any of the generally applicable equitable affirmative defenses, including laches, unclean hands, and estoppel.
II.
Plaintiffs requested that judgment be entered on behalf of the entire class for the aggregate amount of the security deposits retained, and suggested that any amounts not ultimately claimed by individual class members should escheat to the state. The trial court rejected the request and entered judgment in favor of only those members of the class (excluding the named plaintiffs, whose claims were dealt with separately) who might actually come forward and file individual claims. In doing so, the court issued a memorandum of intended decision stating in pertinent part: “In certain consumer class actions Fluid Recovery may be the best method of compensating the class. The propriety of Fluid Recovery in a particular case depends upon its usefulness in fulfilling the purposes of the underlying cause of action. (See State v. Levi Strauss & Co. [1986] 41 Cal.3d 460 [224 Cal.Rptr. 605, 715 P.2d 564].) We do not find that the Fluid Recovery method is necessary to fulfill the purposes of this case.”7 Plaintiffs now contend that the trial court abused its discretion by denying the remedy they requested.
“The class action is a product of the court of equity—codified in section 382 of the Code of Civil Procedure. It rests on considerations of necessity and convenience, adopted to prevent a failure of justice.” (City of San Jose v. Superior Court, supra, 12 Cal.3d 447, 458.) In 1994 the Legislature amended Code of Civil Procedure section 384, providing guidelines for the courts to use in exercising their equitable discretion to shape class remedies. Subdivision (b) of this statute declares that unless the defendant is a public entity or public employee, “prior to the entry of judgment in a class [751]*751action ... the court shall determine the total amount that will be payable to all class members, if all class members are paid the amount to which they are entitled pursuant to the judgment. The court shall also set a date when the parties shall report to the court the total amount that was actually paid to the class members. After the report is received, the court shall amend the judgment to direct the defendant to pay the sum of the unpaid residue, plus interest on that sum at the legal rate of interest from the date of the entry of the initial judgment, in any manner the court determines is consistent with the objectives and purposes of the underlying cause of action . . . .” In subdivision (a) of Code of Civil Procedure section 384, the Legislature explains that its intent in enacting the foregoing statute was “to ensure that the unpaid residuals in class action litigation are distributed, to the extent possible, in a manner designed either to further the purposes of the underlying causes of action, or to promote justice for all Californians.” However, the Legislature makes it clear that nothing in the statute “shall ... be construed to abrogate any equitable cy pres remedy which may be available in any class action with regard to all or part of the residue.” (Id., subd. (d).)
When the trial court chose the class remedy in this case, it had already held that defendants were not entitled to set off amounts owed for unpaid rent, repair, and cleaning. There can be little doubt that this prior ruling was among the more important factors that the trial court considered in deciding what remedy would be most equitable given the circumstances as they then existed. However, we now hold in part I of this opinion that the trial court’s initial ruling was error, that defendants are not barred as a matter of law from seeking setoff, and that they are entitled to have the opportunity to prove their right to setoff at an evidentiary hearing. It follows that the equities in this case may well have changed, and the trial court must reconsider its choice of remedy in light of the result of the forthcoming evidentiary hearing on defendants’ claim of setoff.
III.
The judgment provided in part that “Plaintiffs shall recover legal costs in the amount of $_[to be hereafter determined by the court]. Plaintiffs’ counsel shall recover reasonable attorneys’ fees in an amount to be hereafter determined by the Court. Such court costs and attorneys’ fees shall be paid out of and deducted from any aggregate amount of money paid by Islay under this judgment as the refund of rent for the first 31 days of a tenancy (when compared with the rent for the second and subsequent months of the tenancy). Pursuant to the notice given potential class members, such court costs together with such attorneys’ fees shall not exceed 25% of said aggregate amount.”
[752]*752Plaintiffs contend the 25 percent limitation on attorney fees was an abuse of discretion because the court failed to obtain and consider evidence regarding the number of hours class counsel devoted to the litigation, counsel’s normal hourly rates, counsel’s experience, or the quality of the legal services provided. This contention is premature because it is impossible to determine whether attorney fees in the amount of 25 percent of the “aggregate class recovery” are adequate, given that (1) the amount of defendants’ offsets, if any, have not yet been calculated, and it is therefore impossible to determine what the total class recovery will be, if anything, and (2) this case is far from over, and it is therefore impossible to determine the total number of hours class counsel will devote to it prior to completion.
We have held, and we remain convinced, that an “ ‘experienced trial judge is the best judge of the value of professional services rendered in his court....’” (Serrano v. Priest (1977) 20 Cal.3d 25, 49 [141 Cal.Rptr. 315, 569 P.2d 1303].) Accordingly, the trial court must reconsider the question of attorney fees after the forthcoming evidentiary hearing on defendants’ claim of setoff.
The judgment of the Court of Appeal is reversed insofar as it impliedly affirms (1) that portion of the judgment of the trial court which limits recovery to nonnamed class members who have not opted out and who file claims, and (2) that portion of the judgment which limits the amount of the award of costs and attorney fees. The Court of Appeal shall remand the cause to the trial court with directions to conduct further proceedings consistent with this opinion. In all other respects the judgment of the Court of Appeal is affirmed.
Lucas, C. J., George, J., and Werdegar, J., concurred.