In City of Manila v. Laguio, Jr., this Court expounded the meaning and scope of equal protection, thus:
Equal protection requires that all persons or things similarly situated should be treated alike, both as to rights conferred and responsibilities imposed. Similar subjects, in other words, should not be treated differently, so as to give undue favor to some and unjustly discriminate against others. The guarantee means that no person or class of persons shall be denied the same protection of laws which is enjoyed by other persons or other classes in like circumstances. The “equal protection of the laws is a pledge of the protection of equal laws.” It limits governmental discrimination. The equal protection clause extends to artificial persons but only insofar as their property is concerned.
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Legislative bodies are allowed to classify the subjects of legislation. If the classification is reasonable, the law may operate only on some and not all of the people without violating the equal protection clause. The classification must, as an indispensable requisite, not be arbitrary. To be valid, it must conform to the following requirements:
1) It must be based on substantial distinctions.
2) It must be germane to the purposes of the law.
3) It must not be limited to existing conditions only.
4) It must apply equally to all members of the class.