dissenting.
I agree with Mr. Justice Saylor’s conclusion that the question here involves the authority of the Civil Service Commission pursuant to its enabling legislation, the Civil Service Act, to enforce the veterans’ preference provisions of the Military Affairs Act. However, because, I disagree that the Commission possesses such authority, I respectfully dissent.1
The Chester County Housing Authority, the appointing authority, hired Troy L. Chapman as its executive director. The Housing Authority did so in compliance with the Civil Service Act, as that Act requires the appointing authority to select a candidate for hire from among the three highest ranking persons for the position appearing on an employment list. Specifically, Section 602 of the Act, known as the “Rule-of-Three,” provides in relevant part:
If the vacant position is to be filled from among the names of persons certified from the employment list by the director to the appointing authority, he shall elect a person from among the three highest ranking persons for the class of position to be filled....
71 P.S. § 741.602. Here, it is not the veteran candidate, John Fitzgerald, who is complaining about the appointing authority’s hiring decision, rather it is the Civil Service Commission itself that is attempting to enforce the veterans’ preference provisions of the Military Affairs Act. The Commission, however, as a Commonwealth agency is limited to the powers granted by the legislature pursuant to its enabling legislation. See Pa. Human Relations Commission v. Zamantakis, 478 Pa. 454, 387 A.2d 70, 72 (1978) (stating that this Court has said many times that administrative agencies “can only exercise those powers which have been conferred upon [them] by the Legislature”). Here, the applicable legislation is the Civil Service Act. Nowhere in the Civil Service Act is the Commission granted the explicit authority to enforce the veterans’ preference provisions of the Military Affairs Act.
Despite the lack of explicit authority in the Civil Service Act, the Commission, nevertheless, promulgated Management Directive 580.21 in an attempt to incorporate the veterans’ preference provisions of the Military Affairs Act into the Civil Service Act. As noted by the majority, “the crux of this matter is whether Management Directive 580.21 Amended, which essentially incorporates section 7104(b) of the Military *951Affairs Act, was validly enacted by the Commission.” Majority Opinion at 942. If so, the Commission has the authority to enforce it sua sponte.2 As further noted by the majority, “[s]ince the Management Directive at issue is legislative in character, it will be deemed valid and binding if it: (a) is within the granted power; (b) is issued pursuant to proper procedure; and (c) is reasonable.” Majority Opinion at 943, citing Girard School District, 481 Pa. 91, 94-95, 392 A.2d 261, 263 (1978). I disagree with the majority’s conclusion that the substance of Management Directive 580.21 is within the Commission’s granted power. Accordingly, I do not agree that the Commission had the authority here to enforce the veterans’ preference provisions.
Management Directive 580.21, ostensibly was adopted pursuant to the Commission’s legislative rule-making power set forth at Section 203 of the Civil Service Act, which provides in relevant part:
§ 741.203. Duties of Commission
It shall be the duty of members of the Commission as a body—
(1) After public hearing, as hereinafter set forth, to establish, adopt and amend rules, either on its own motion or upon recommendation of the director, for making effective the provisions of this act ....
71 P.S. § 741.203 (emphasis added). “This act” clearly refers to the Civil Service Act. Management Directive 580.21, however, attempts to make effective provisions of the Military Affairs Act. It provides:
2. Policy. Veterans’ preference applies to appointment only as follows:
a. Persons entitled to veterans’ preference under the Military Affairs Act who take civil service examinations for appointment will:
(1) Receive 10 additional points on their final earned ratings.
(2) Have mandatory appointment preference over non-veterans when their names appear together within the Rule-of-Three on employment certifications.
M.D. 580.21 Amended, February 12, 1992.
Management Directive 580.21 clearly conflicts with the explicit statutory mandate of Section 602 of the Civil Service Act, i.e., the Rule-of-Three, in that it requires that veteran candidates be selected over non-veteran candidates. While it may be argued that the Military Affairs Act does, in fact, require that veteran candidates be selected over non-veteran candidates, the question here is who has the authority to mandate such result.3
The majority concludes that because the Commission has the authority to promulgate rules relating to the Civil Service Act and because the purpose of the Act is to establish conditions of service to attract qualified persons, the Commission had the authority to incorporate into the Civil Service Act the express legislative desire that veterans be given mandatory preference in appointment over non-veteran candidates. I disagree.
As previously noted, the Commission has not been delegated such authority by way of the Civil Service Act and, in fact, the explicit statutory requirement of the Civil Service Act, the Rule-of-Three, conflicts "with the veterans’ preference provisions. The legislature could have easily provided for the Commission’s authority to enforce the veterans’ preference provisions as part of its stated duties, but it failed to do so. Moreover, the legislature specifi*952cally set forth the extent of the Commission’s duties relative to veterans’ preference matters in Section 203(5) of the Civil Service Act. This Section provides:
§ 741.203. Duties of Commission
It shall be the duty of members of the Commission as a body—
(5) To report on an annual basis, beginning June 1, 1975 and each June first, thereafter, to the General Assembly on all complaints, grievances, and cases arising from questions by veterans with regard to the application of and the results attained by use of the veterans’ preference provisions of this act with regard to hiring, promotion, and firing of employees covered by this act.
71 P.S. § 741.203(5). This provision limits the Commission’s authority as it relates to veterans’ preference to reporting to the General Assembly on complaints, etc., by veterans. Because the legislature specified the Commission’s duties relating to veterans’ preference, the fundamental maxim of statutory construction, “ expres-sio unius est exclusio alteráis,” applies and stands for the principle that the mention of one thing in a statute implies the exclusion of others not expressed.
Finally, if the majority’s reasoning were taken to its logical conclusion, the Civil Service Commission would be required to promulgate rules whereby veteran candidates are given preference over non-veteran candidates even when the veteran candidate’s name does not appear among the three highest names on an eligibility list. Such requirement would, however, directly violate the express statutory requirement of the Civil Service Act, the Rule-of-Three, which the Commission is unquestionably charged with administering.4
For the forgoing reasons, contrary to the majority, I would reverse the decision and order of Commonwealth Court insofar as it holds that the Commission has the authority to enforce the veterans’ preference provisions of the Military Affairs Act.
Justice CAPPY and NIGRO join this Dissenting Opinion.
. The majority concludes that the Commission possesses such authority and therefore has standing.
. See 71 P.S. § 741.203(3) (the Commission has the duty to require observance of the provisions of this act and the rules and regulations thereunder).
. Based on my conclusion that the Commission lacks authority to enforce the veterans’ preference provisions of the Military Affairs Act, I would not reach the issue of whether the Military Affairs Act does, in fact, mandate that veteran candidates be selected over a non-veteran candidates.
. Significantly, the majority concedes that the Military Affairs Act conflicts with the Rule-of-Three because it would require that any veteran candidate appearing on an eligibility list be given preference whether or not his or her name was among the three highest ranked candidates. See Majority Op. at 944.