The classification of cities into highly urbanized and component cities based on annual income under Batas Pambansa Blg. 51, which determines whether their residents can vote for provincial officials, is based on substantial distinctions germane to the constitutional mandate of promoting local autonomy and does not violate the equal protection clause or the right of suffrage.

Following the enactment of the 1973 Constitution emphasizing local government autonomy, the Interim Batasan Pambansa passed Batas Blg. 51 in preparation for the January 30, 1980 local elections. This law introduced a classification system for cities based on annual income (P40 million threshold) into "highly urbanized" and "component" cities. This classification determined whether the registered voters of a city could participate in the election of officials of the province where the city is geographically located, leading to challenges from voters in affected cities like Cebu and Mandaue.

• On December 22, 1979, Batas Pambansa Blg. 51 was enacted for the 1980 local elections.
• Section 3 of Batas Blg. 51 classified cities with an annual income of at least P40 million as "highly urbanized cities" and stipulated that their registered voters could not vote for provincial officials.
• All other cities were considered "component cities," whose voters could vote for provincial officials only if their respective charters allowed it.
• Baguio City was classified as highly urbanized regardless of income due to its special status.
• Cebu City, with an income over P51 million, was classified as highly urbanized, thus its voters were barred from voting for provincial officials of Cebu Province, despite its City Charter (Commonwealth Act No. 58, as revised by RA 3857) previously allowing it.
• Mandaue City, not meeting the income threshold, was a component city, but its Charter (Republic Act No. 5519, Section 96) expressly prohibited its registered voters from participating in the election of provincial officials of Cebu Province.
• The Commission on Elections (COMELEC) issued Resolution No. 1421 implementing Batas Blg. 51, listing cities (including Cebu and Mandaue) whose voters were not entitled to vote for provincial officials.
• Petitioners, taxpayers and registered voters from Cebu City and Mandaue City, challenged the constitutionality of Section 3 of Batas Blg. 51 and Section 96 of RA 5519.

• Section 3 of Batas Blg. 51 is unconstitutional because classifying cities based solely on income to determine voting rights for provincial officials is not based on substantial distinctions germane to the purpose of the law (regulating suffrage) and thus violates the equal protection clause.
• Republic Act No. 5519 (Charter of Mandaue City) is unconstitutional because it took effect without ratification by Mandaue residents in a plebiscite, allegedly required by the Constitution.
• Denying Mandaue City voters the right to vote for provincial officials while allowing voters in other component cities this right constitutes a denial of equal protection.
• Prohibiting city voters from voting for provincial officials imposes a substantial requirement on the exercise of suffrage and violates the sanctity of the ballot, contrary to Article VI, Section 1 of the 1973 Constitution.
• The prohibition subverts the principle of republicanism by depriving citizens of their right to participate in the conduct of government affairs (provincial government).
• The passage of Batas Blg. 51 and Section 96 of the Mandaue Charter were motivated by political gerrymandering aimed at disenfranchising opposition voters in Cebu City and Mandaue City.

• N/A (The decision does not explicitly detail the respondents' counter-arguments, but the Court's ruling implicitly upholds the position of COMELEC, COA, and the National Treasurer that the challenged laws and actions are valid. The Solicitor General's point refuting the gerrymandering claim is noted in the ruling.)

• Is the classification of cities into highly urbanized and component cities based on income under Section 3 of Batas Blg. 51, which affects the right of city residents to vote for provincial officials, violative of the equal protection clause?
• Does denying voters in Mandaue City (a component city) the right to vote for provincial officials, pursuant to its charter, while allowing voters in other component cities this right, violate the equal protection clause?
• Is Republic Act No. 5519 (Charter of Mandaue City) unconstitutional for not having been ratified in a plebiscite?
• Does the prohibition preventing voters in highly urbanized cities and specific component cities (like Mandaue) from voting for provincial officials infringe upon the constitutional right of suffrage and the principle of republicanism?
• Were Batas Blg. 51 and RA 5519 enacted due to political gerrymandering motives?

• The petition is dismissed for lack of merit.
• The classification of cities based on income in Batas Blg. 51 is constitutional; it rests on substantial distinctions, as income reflects a city's capacity for independent existence and development, justifying greater autonomy and detachment from provincial affairs, including elections, consistent with the 1973 Constitution's thrust towards local autonomy.
• There is no denial of equal protection for Mandaue City voters; the difference in voting rights among component cities arises from legislative discretion expressed in their individual charters, a practice upheld in Teves vs. COMELEC. Equal protection is not violated if all voters within the same city are treated equally regarding provincial elections.
• The Charter of Mandaue City (RA 5519) is valid; the constitutional requirement for a plebiscite for city creation or boundary alteration (Art. XI, Sec. 3, 1973 Constitution) is prospective and does not apply to Mandaue City, which was created in 1969 before the 1973 Constitution took effect.
• There is no infringement on the right of suffrage; the Constitution does not grant city voters an inherent right to vote for provincial officials. The prohibition does not impose impermissible burdens on suffrage like poll taxes or discriminatory requirements; voters remain free to vote in city elections. Limiting participation in provincial elections aligns with the reduced connection between highly urbanized cities and the province.
• The claim of gerrymandering lacks factual and legal basis; the challenged laws do not involve the apportionment of representative districts, and no evidence showed an unfair advantage was given to any political party.

• Equal Protection Clause: Definition: Guarantees that all persons or things similarly situated should be treated alike, both as to rights conferred and responsibilities imposed. Classification is permitted if based on substantial distinctions, germane to the purpose of the law, not limited to existing conditions only, and applies equally to all members of the same class. Application: The Court found the income-based classification of cities under Batas Blg. 51 met these requirements, as income is a substantial distinction related to a city's autonomy and capacity for self-governance, justifying differential treatment regarding participation in provincial elections. The difference in voting rights for Mandaue voters stemmed from its specific charter, a valid exercise of legislative discretion, not a violation of equal protection among Mandaue voters themselves.
• Local Autonomy: Definition: The principle that local government units should possess a degree of self-governance and independence from central or higher-level government control, particularly in managing their own affairs. Application: The Court emphasized that the 1973 Constitution promotes local autonomy. Classifying highly urbanized cities as independent from provincial supervision and limiting their participation in provincial elections were seen as consistent with enhancing their autonomy due to their greater economic capacity and distinct administrative needs.
• Substantial Distinction: Definition: A standard used in equal protection analysis requiring that any classification must be based on real differences relevant to the law's purpose. Application: The Court held that a city's annual income constitutes a substantial distinction because it indicates the city's economic viability, complexity, and capability to operate independently from the province, thus justifying the distinction made by Batas Blg. 51 regarding voting rights in provincial elections.
• Legislative Discretion: Definition: The power vested in the legislature to make policy choices and enact laws, including determining the specific provisions of city charters, within constitutional limits. Application: The Court recognized that the legislature has the discretion to grant or withhold the right of component city residents to vote for provincial officials through the city's charter, as seen in the case of Mandaue City (RA 5519) and discussed in Teves vs. COMELEC.
• Prospectivity of Laws: Definition: The principle that laws generally operate only on acts, events, or rights arising after their enactment and do not retroactively affect vested rights or past events unless expressly provided and not constitutionally prohibited. Application: The Court applied this doctrine to hold that the plebiscite requirement for city creation under the 1973 Constitution (Art. XI, Sec. 3) could not invalidate the Charter of Mandaue City (RA 5519), as the city was created in 1969 before the 1973 Constitution took effect.
• Right of Suffrage: Definition: The right of qualified citizens to vote in elections. Application: The Court clarified that the right of suffrage is not absolute and does not constitutionally guarantee city residents the right to vote for provincial officials. The prohibition in Batas Blg. 51 and RA 5519 was not considered an impermissible burden on suffrage because it did not restrict the right to vote for city officials or impose qualifications beyond residency and registration.
• Republicanism: Definition: A principle of government where sovereignty resides in the people and is exercised through representatives chosen by them. Application: The Court rejected the argument that denying city voters the right to vote for provincial officials subverts republicanism, reasoning that since highly urbanized cities are independent of provincial government supervision, limiting the selection of provincial officials to those directly affected (provincial residents and voters in component cities whose charters allow it) is just and proper.

• "The classification of cities into highly urbanized cities and component cities on the basis of their regular annual income is based upon substantial distinction. The revenue of a city would show whether or not it is capable of existence and development as a relatively independent social, economic, and political unit."
• "Corollary to independence however, is the concomitant loss of the right to participate in provincial affairs, more particularly the selection of elective provincial officials since these provincial officials have ceased to exercise any governmental jurisdiction and authority over said city."
• (Quoting Teves vs. Commission on Election): "The purpose of an election is to enable the electorate to choose the men that will run their government, whether national, provincial, municipal or city. If so, no useful end will be served by allowing - in the absence of express legislative preference - the voters of a city to participate in the election of the officials of the province which has ceased to have any governmental jurisdiction and authority over said city."
• "The equal protection of the law contemplates equality in the enjoyment of similar rights and privileges granted by law. It would have been discriminatory and a denial of the equal protection of the law if the statute prohibited an individual or group of voters in the city from voting for provincial officials while granting it to another individual or group of voters in the same city."
• "Neither can it be considered an infringement upon the petitioners' rights of suffrage since the Constitution confers no right to a voter in a city to vote for the provincial officials of the province where the city is located."

• Teves vs. Commission on Election, 90 Phil. 370: Cited as controlling precedent establishing that voters of a city (Dumaguete) that is politically independent of the province are not entitled to vote for provincial officials unless the city charter expressly grants such right. Used to justify denying Cebu City voters the right (as a highly urbanized city) and Mandaue City voters the right (due to its charter).
• Harper vs. Virginia Board of Elections, 383 U.S. 663: Cited as an example of an impermissible burden on the right of suffrage (invalidated Virginia poll tax). Distinguished from the present case, where no similar financial or burdensome requirement was imposed on Cebu or Mandaue voters.
• Kramer vs. Union Free School Dist., 395 U.S. 621: Cited as another example of an unconstitutional restriction on suffrage (invalidated requirement for voting in school district elections). Distinguished, as the prohibition on voting for provincial officials in this case was deemed rationally related to the city's autonomy and independence from the province.
• Magtoto vs. Manguera, 63 SCRA 4: Cited to support the principle of prospectivity, specifically that constitutional provisions (like the plebiscite requirement in the 1973 Constitution) generally apply prospectively and do not affect rights or statuses established before their effectivity. Used to uphold the validity of the Mandaue City Charter created before 1973.

• Batas Pambansa Blg. 51, Section 3: The primary statute challenged, classifying cities into highly urbanized and component based on income and defining voting rights for provincial officials accordingly. Its constitutionality was upheld.
• Republic Act No. 5519 (Charter of Mandaue City), Section 96: Challenged provision expressly prohibiting Mandaue voters from participating in provincial elections. Its validity was upheld.
• 1973 Constitution, Article II, Section 10: Cited regarding the State policy to guarantee and promote local government autonomy. Used to support the rationale behind Batas Blg. 51.
• 1973 Constitution, Article XI, Section 2: Cited regarding the mandate for the National Assembly to enact a local government code. Contextualizes the legislative actions concerning local governments.
• 1973 Constitution, Article XI, Section 3: Cited for the plebiscite requirement for the creation, division, merger, abolition, or boundary alteration of local government units. Held inapplicable to Mandaue City's creation as it was prospective.
• 1973 Constitution, Article XI, Section 4(1): Cited regarding the classification of cities and the independence of highly urbanized cities from provincial supervision. Central to the Court's reasoning on autonomy.
• 1973 Constitution, Article XI, Section 5: Cited regarding the power of local governments to create revenue sources and levy taxes. Part of the constitutional framework for local autonomy.
• 1973 Constitution, Article VI, Section 1: Cited by petitioners regarding the right of suffrage and sanctity of the ballot. The Court found no violation of this provision.
• Commonwealth Act No. 58 (as revised by Rep. Act No. 3857): Mentioned as the Charter of Cebu City, which previously allowed its voters to participate in provincial elections before Batas Blg. 51.