This action involves Ada County and three of its municipalities, Boise, Garden City and Eagle. The controversy arose under Idaho’s Local Planning Act of 1975, Chapter 65, Title 67, Idaho Code. Pursuant to I.C. § 67-6526(c) of that act, the governing board of each city was required on or before January 1, 1978, to adopt by ordinance a map identifying the area of city impact within the unincorporated areas of Ada County. The object of this requirement was to delineate areas of future contiguous growth in order to assure their orderly development and thereby reconcile potentially competing designs for boundary expansion with accepted land use planning principals.
The areas of city impact adopted by the three cities (were in conflict; the ordinances of each city resulted in overlapping impact area boundaries. The local planning act made provision for settlement in such eventuality. As a first step, it provided for negotiation between the cities. In the event negotiations failed, the second step provided for reference to the Board of County Commissioners which, after consulting the affected cities, was to recommend adjustment. If any city objected to the county commissioner’s recommendations, then the act provided that the city objecting could “seek a declaratory judgment from the district court adjusting the areas of city impact.”
Upon concluding the negotiation phase, Garden City objected to the adjustments recommended by Ada County, and thereafter instituted this action requesting that the district court adjust Boise’s area of impact to eliminate those areas lying within the boundaries of Garden City’s proposed impact area.
In 1979, while this action was pending, the legislature amended I.C. § 67-6526 eliminating recourse to district court as a means of settling overlapping impact area disputes. The act now provides that if any city objects to the adjustment recommendations of the county commissioners a special election shall be conducted within sixty days for the purpose of submitting to the qualified electors residing in the overlapping impact area the determination in which city’s area of impact they wish to be included. The amendment further provides that the results of the election are conclusive and binding without any appeal.
On June 25, 1979, Boise filed a motion to compel election pursuant to the statute as amended. Following hearing and submission of briefs by the parties, the trial court issued a memorandum decision and'order, dismissing the case in its entirety for want of jurisdiction.
The issues presented on this appeal are:
(1) Whether the 1979 amendment to the area of city impact provision of the Local Planning Act substituting a special election in lieu of a declaratory judgment action as a means of adjusting overlapping impact areas may be applied retroactively.
(2) Whether the 1979 amendments to the area of impact provisions of the Local Planning Act are in violation of the Constitution of the State of Idaho.
(3) Whether substitution of the electoral process as a means of resolving local planning disputes constitutes an unlawful delegation of police powers.
(4) Whether the district court erred in failing to address the other constitutional issues raised by Garden City.
*515I
Generally a statute will not be applied retroactively in the absence of clear legislative intent to that effect. I.C. § 73-101. Johnson v. Stoddard, 96 Idaho 230, 526 P.2d 835 (1974). However, it also is the rule in Idaho that retroactive legislation is only that which affects vested or already existing rights. Hidden Springs Trout Ranch, Inc., v. Allred, 102 Idaho 623, 624, 636 P.2d 745, 746 (1981); Buckalew v. City of Grangeville, 100 Idaho 460, 600 P.2d 136 (1979).
Remedial or procedural statutes which do not create, enlarge, diminish or destroy contractual or vested rights are generally held to operate retrospectively. Ohlinger v. U.S., 135 F.Supp. 40 (D.C.Idaho 1955).
“A statute merely affecting the remedy may apply to, and operate on, causes of action which had accrued and were existing at the time of the enactment of the statute, as well as causes of action thereafter to accrue, and to all actions, whether commenced before or after its enactment. 82 C.J.S., Statutes, § 421; 11 Am. Jur., Constitutional Law, §§ 373 and 382.” Id.
Garden City has no inherent right of its own to annex property. In Caesar v. State, 101 Idaho 158, 160, 610 P.2d 517, 519 (1980), this court stated:
“Our analysis of this issue necessarily involves a review of the basic tenets of municipal corporation law. Idaho has long recognized the proposition that a municipal corporation, as a creature of the state, possesses and exercises only those powers either expressly or impliedly granted to it. [Citations omitted.] ... Thus, under [the] rule, a municipal corporation may exercise only those powers granted to it by either the state constitution or the legislature and the legislature has absolute power to change, modify or destroy those powers at its discretion. State v. Steunenberg, 5 Idaho 1, 4, 45 P. 462, 463 (1896).”
In amending I.C. § 67-6526, the legislature exercised its power to modify a municipality’s powers by substituting the electoral process for the declaratory judgment action.
II
Next, Garden City urges that the amendment to I.C. § 67-6526(c) is unconstitutional in that it deprives both Garden City and the property owners in the overlapping impact areas of due process and equal protection. Garden City lacks standing to assert the rights of property owners in the overlapping impact area and the city itself has no vested rights for the reasons set forth in part I above.
III
Garden City argues that the substitution of the electoral process is an unlawful delegation of police power, alleging it is improper to have the election determine these matters. The cases relied on by Garden City for this proposition concern alleged unconstitutional delegation of zoning power to adjoining land owners, which circumstance is not involved here. Those cases dealt with zoning regarding uses of land, i.e., consent of adjoining landowners to obtain a construction permit, liquor license, construct a multiple dwelling, an apartment building, and a mobile home park.
In this case, all electors within the impact area are permitted to vote — no power is unconstitutionally delegated to one neighbor to determine the limitation on another’s use of his land.
IV
Finally, Garden City argues that the district court erred in failing to address the other constitutional issues raised in its declaratory judgment action. Garden City sought to have the Local Planning Act of 1975 declared unconstitutional in its entirety. It is a firmly established principle of *516law, of uniform application, that the constitutionality of a statute may not be questioned by one who has voluntarily claimed and accepted its benefits. State v. City of Gooding, 75 Idaho 36, 266 P.2d 655 (1953). Garden City is availing itself of the benefits of the Local Planning Act by establishing impact areas pursuant to that act, and it cannot simultaneously contend that the act is unconstitutional.
The order of dismissal is affirmed. No costs or attorney fees allowed.
DONALDSON, C.J., and BAKES, J., concur. SHEPARD, J., concurs in the result.