(dissenting). This case presents a question of statutory construction. The precise issue is whether worker’s compensation benefits should be included within the definition of “compensation” as codified in the Public School Employees Retirement Act, MCL 38.1301 et seq.) MSA 15.893(111) et seq. The resolution of this question affects whether a public school employee will be given “service credit,” and thus an enhanced retirement benefit, for any time *339spent off work while receiving worker’s compensation benefits.
The Michigan Public School Employees Retirement Board determined, first in a contested case and then by declaratory ruling, that worker’s compensation payments were in the nature of “compensation” and, accordingly, the time an employee receives worker’s compensation counts toward earning retirement credit. On appeal, the Court of Appeals reversed the board’s ruling, finding that worker’s compensation is not “compensation” under the clear and unambiguous definition of that term in the act. I believe that the majority errs in reversing the decision of the Court of Appeals and reinstating the declaratory ruling of the board. At its core, this is a case where a compelling situation led the board to stray from the mandate of the statute. This Court has now, by ratifying that ruling, compounded the error by failing to fulfill its duty to apply the statute as written.
FACTS
The genesis of the instant dispute was a contested case initiated by Bessie Traylor. Having worked as a school teacher for nearly thirty years, she planned to teach one more year before retiring. Unfortunately, at the outset of this last year of work she was injured on the job and was not able to teach for the remainder of the year. While off work she received worker’s compensation benefits. On the date of her injury she had accrued approximately 29.8 years of service credit. Under the interpretation of the act employed by the Michigan Public School Employees Retirement System at the time, Ms. Traylor was not given service credit for the time spent off work while receiving *340worker’s compensation payments. As a result, at the end of the year she failed to accrue at least thirty years of service credit, and, not meeting that threshold, her retirement benefit was approximately $250 per month less than it would have been had she been given service credit for that period.
Ms. Traylor contested the retirement system’s refusal to award her service credit for the time she was off work and received worker’s compensation benefits. The board, giving the retirement act a reading that was unprecedented in that agency’s construction of the statute, determined that Ms. Traylor should be given service credit for the time she received worker’s compensation. The board’s reasoning was that this benefit was in some sense similar to sick pay, and because sick pay falls under the statutory definition of “compensation,” so should worker’s compensation. This approach ensured that Ms. Traylor would receive the full pension she would have obtained had she not been injured.
Not surprisingly, this ruling caused those charged with implementing teacher retirements to inquire of the board how this ruling would affect others similarly situated. The board at that point chose a course consistent with the Traylor holding and indicated that it planned to implement this new treatment of worker’s compensation benefits system wide for those who were paid worker’s compensation benefits, commencing March 13, 1992, as well as for active public school employees who applied for service credit for periods before that date. This litigation ensued, and this Court has now affirmed the validity of the board’s ruling. This means that teachers who received worker’s compensation benefits from *341March 13, 1992, through June 12, 1996, will automatically receive retirement credit for that period.
STANDARD OF REVIEW
In reviewing the ruling of an administrative agency, our first duty is to determine whether the agency ruling is violative of the statute in question. That is, has the agency followed the law? If it has not, it must be overturned, because the mandate of the Legislature must be controlling over any contrary determination of the agency. MCL 24.306(l)(a); MSA3.560(206)(l)(a); Southfield Police Officers Ass’n v Southfield, 433 Mich 168, 175; 445 NW2d 98 (1989); Amalgamated Transit Union, Local 1564, AFL-CIO v Southeastern Michigan Transportation Authority, 437 Mich 441, 450; 473 NW2d 249 (1991).
DISCUSSION
As prefaced above, the controversy concerns the statutory definition of “compensation” as formerly codified at MCL 38.1304(1); MSA 15.893(114)(1). That subsection defined “compensation” for purposes of computing retirement credit:
“Compensation” means the remuneration earned by a member for service performed as a public school employee. When part of a member’s remuneration is not paid in money, the retirement board shall fix the value of that part of the remuneration not paid in money. Compensation shall include, on a current basis, investments made in a tax sheltered annuity for a public school employee as remuneration for service under this act. The remuneration shall be valued at the amount of money actually paid into the annuity. Compensation shall include all amounts deducted from the pay of a public school employee. Compensation shall include longevity pay, overtime pay, vacation pay, and holiday pay while absent from work, sick leave pay while absent from *342work, and items of deferred compensation, exclusive of employer contributions to the retirement system. Compensation shall exclude terminal payments for unused sick leave, annual leave, bonus payments, hospitalization insurance and life insurance premiums, other fringe benefits paid by and from the funds of employers of public school employees, and remuneration paid for the specific purpose of increasing the final average compensation.
As is apparent, “compensation” was broadly defined by the Legislature. The myriad types of benefits contractually conferred on the employee by the employer were included. The Legislature endeavored to list such payments as employer contributions to tax sheltered annuities, remuneration not paid in money, and finally all amounts deducted from the employee’s paycheck as items falling within the definition of “compensation.” However, the Legislature further refined the definition of “compensation” by removing certain items that would have fallen within the general definition absent specific exclusion. Thus, terminal payments for unused sick leave, annual leave, bonus payments, hospital and life insurance premiums, and other fringe benefits were excluded from the definition of compensation.
In this manner the Legislature comprehensively defined the scope of what is, and what is not, compensation. We do not have authority to expand, or contract, its definitions. The reason, formally, is the rule of statutory construction known as expressio unius est exclusio alterius, which means that the express mention of one thing is the exclusion of the other.1 That is what the Legislature has done here. *343The statute defines compensation as remuneration earned by a public school employee, including investments made in tax sheltered annuities, amounts deducted from the pay of a public school employee, longevity pay, overtime pay, vacation pay, holiday pay, sick leave pay, and items of deferred compensation, exclusive of employer contributions to the retirement system. Noticeably absent is any mention of worker’s compensation benefits or any invitation to expand the class of included items by use of a catchall suggesting similar items could be included. This means the Legislature demonstrated that it did not intend to include worker’s compensation benefits within that definition.* 2
Additionally, review of the entire act demonstrates that the Legislature considered the concept of providing service credit for the time an employee receives worker’s compensation benefits and, in some circumstances, decided to grant it. MCL 38.1387; MSA *34415.893(197) directs that employees will receive service credit for periods off work while receiving worker’s compensation payments if, after becoming totally and permanently disabled because of a work-related injury, the member recovers from the disability and returns to work. In addition, MCL 38.1390; MSA 15.893(200) directs that if a member receives worker’s compensation because of a work-related injury and subsequently dies from the work-related injury, the surviving spouse’s retirement allowance will be computed by giving the deceased member service credit for the time up to the date of death. It is apparent then, that the Legislature granted retirement credit for worker’s compensation benefits in some circumstances and not in others. This would seem to compel this Court to follow the pattern the Legislature has established or, failing to do so, to advance some reason to justify this departure from deference to the Legislature. No such reason has been offered by the majority. By deciding this case in this fashion, it is unfortunate but inescapable that we have destroyed the nuanced treatment of worker’s compensation benefits that the Legislature mandated in §§ 87 and 90. I believe we clearly have no authority to do this and therefore should not.
In response to this statutory analysis, the majority is either silent or simply relies on the argument that sick leave pay and worker’s compensation are functionally synonymous, and therefore we ought to treat them similarly because sick leave pay is specifically included within the statutory definition of compensation. Having already discussed how the majority has simply misread or disregarded the statute, I also find that the so called “similarity” approach will not bear *345serious examination. The simple reason is that sick pay and worker’s compensation are highly dissimilar in their effect on pension benefits. These differences should dissuade this Court in this case, which concerns pensions, from treating these distinct items as fungible.
It is of course the case that statutorily required worker’s compensation payments can be awarded for an indeterminate amount of time, while employer-employee negotiated sick leave pay is a benefit that has a fixed maximum duration no matter the nature or duration of an employee’s illness. That is, whether there even is sick leave pay, as well as the extent of the employer’s liability for sick leave pay, is always calculable and finite. Sick leave pay then lends itself to actuarial certainty, a crucial matter when funding pensions. The benefits and duration of worker’s compensation, however, have no comparable certainty. Clearly, no one conversant with pensions and their funding would lightly discount this distinction between open-ended versus defined benefits and call them “similar.” Moreover, it seems that the Legislature understood this important distinction, which is central to pension funding, because the two instances in which the Legislature granted retirement credit for the time an employee received worker’s compensation (the already discussed §§87 and 90) both are when the worker’s compensation benefit period is finite. In § 87, the period of credit is the period from total disability to recovery and return to work. In § 90, it is from time of disability to death from the work-related injury. This means then that the Legislature manifested, by the fact that it only treated time while receiving worker’s compensation as a retire*346ment credit when the time was finite, that it did not in any other situation think that worker’s compensation and sick leave pay (which is always finite) were similar. This distinction should be recognized by this Court and reflected in our handling of this matter.
Thus, the cornerstone of the majority’s analysis, the equating of worker’s compensation to sick leave pay, is flawed as a conceptual and practical matter from the outset and should be spumed. Indeed, aware of these dissimilarities, it should cause us, as a matter of comity with the Legislature, to respectfully conclude that the Legislature for these very reasons did not include worker’s compensation within the definition of compensation as defined in 1980.3 We should do this because it is the Legislature that has authority to draw distinctions so as to narrow or widen the scope of legislation. This power derives from the grant of legislative authority given expressly to the Legislature in our constitution. Const 1963, art 4, § 1. Lamentably, the majority has not shown such deference.
Next, I turn to the import of the 1996 amendment of the statute. As is outlined in the majority opinion, the Legislature amended the definition of compensation in 1996 to specifically include worker’s compensation benefits within the definition of compensation. MCL 38.1303a(2)(f); MSA 15.893(113a)(2)(f). The majority holds that this was a mere clarification of the earlier statute and as such a ratification of the board’s ruling. The thrust of this analysis is to reinforce the majority’s assertion that the earlier act should be read as having compensation include credit *347for worker’s compensation. The argument that this amendment is a clarification is, in my view, untenable.
It is recognized that a change by amendment in the phraseology of a statute is presumed to indicate, in the absence of a manifest intent to the contrary, a legislative purpose to change the meaning. Detroit Edison Co v Dep’t of Revenue, 320 Mich 506, 518; 31 NW2d 809 (1948). We deal with that situation here and should understand that a change in meaning was intended. Further, it is axiomatic when ascertaining legislative intent, that the relevant intent “ ‘is the one entertained by the legislature at the time of the passage of the act, and not the intent expressed by a subsequent amendment. ... [T]o interpret the subsequent amendment as an indication of the legislature’s original intent would be mere speculation, not judicial construction.’ ” Id., p 519, quoting Iron Street Corp v Unemployment Compensation Comm, 305 Mich 643, 655; 9 NW2d 874 (1943).
Accordingly, in compliance with the doctrines governing the effect of amendments, the 1996 change in statutory language does not support the conclusion that worker’s compensation payments were included, from 1980 onward, within the definition of “compensation” because we should presume that the change in statutory language effected a change in meaning.
However, even if one adopts the view that the 1996 amendment is a clarification, I do not believe it can be given retroactive effect. The Legislature, while voting to give the 1996 amendment immediate effect, did not include language indicating it wanted to give it retroactive effect. This means retroactive effect should not be given. As we said in Hughes v Judges’ *348Retirement Bd, 407 Mich 75, 84; 282 NW2d 160 (1979), “[T]his Court has not countenanced retrospective application of statutory enactments absent legislative direction to do so
The fact that the Legislature in 1996, after considering effective dates, did not give the statute retroactive effect should be seen as determinative. The majority, however, with little analysis and indeed almost casualness, gives it retroactive effect. This demonstrates that the majority, unlike the Legislature, apparently fails to adequately appreciate the inherent injustice of retroactive legislation. That injustice is that retroactivity poses a fundamental contradiction with the purpose of the law itself: the protection of legitimate expectations. As I have previously discussed “the concept and purpose of law itself ... is to enable our citizens, and those who advise them, to know prospectively what the law is and thus to be able to conform their conduct to what it requires.” Hagerman v Gencorp Automotive, 457 Mich 720, 757; 579 NW2d 347 (1998) (Taylor, J., dissenting). This deprivation of legitimate expectations has happened to the plaintiff and other school boards similarly situated.
Michigan’s school boards have relied in the past on the well understood meaning of the act. They have budgeted and contracted with their employees with the legitimate expectation that, unlike sick leave pay and other forms of statutory “compensation,” no pension funding liability was tied to worker’s compensation benefits. Now the majority imposes that responsibility, by ruling, in the face of the language and structure of the statute, as well as the manifested intent of the enacting Legislature, that the 1980 legislation included from its inception worker’s compensa*349tion payments within the definition of “compensation.” The problems this ruling will surely precipitate could have been avoided if the majority had simply relied on basic doctrines of statutory construction as did the Court of Appeals. Had we done so we, as the Court of Appeals before us, would have reversed the decision of the board. This we should have done. I would affirm the decision of the Court of Appeals.
Brickley and Weaver, JJ., concurred with Taylor, J.A good example of this rule, which makes its application clear, is found in United States Supreme Court Justice Antonin Scalia’s book A *343Matter of Interpretation (Princeton: Princeton Univ Press, 1997): “If you see a sign that says children under twelve may enter free, you should have no need to ask whether your thirteen-year-old must pay.” Id., p 25.
I respectfully suggest that, although unexpressed, the majority has relied upon, and misapplied, the rule of statutory construction known as ejusdem generis, which applies where there are general terms modified by more specific terms. This also has been discussed by Justice Scalia in A Matter of Inteipretation as a rule that means “of the same sort.” He demonstrated this rule by this understandable example, “if someone speaks of using ‘tacks, staples, screws, nails, rivets, and other things,’ the general term ‘other things’ surely refers to other fasteners.” Note 1 supra, p 26. That this rule has been misapplied by the majority can be seen in its opinion where it conflates sick leave pay with worker’s compensation benefits even though there is no specific listing followed by a general category that could be held to encompass worker’s compensation benefits.
Furthermore, to the extent that the majority relies on “legislative history” to support its conclusion, I make reference to my dissent in Hagerman v Gencorp Automotive, 457 Mich 720, 750; 579 NW2d 347 (1998). As explained therein, the Court errs by using a report generated by legislative staff personnel as authority to abrogate the clear language of a statute.
See O’Brien v Hazelet & Erdal, 410 Mich 1, 17; 299 NW2d 336 (1980), and Shavers v Attorney General, 402 Mich 554, 614; 267 NW2d 72 (1978).