The "sana all" doctrine

Atty. Racma Fernandez-Garcia, in one of her law school lectures for her fourth year (review) students, mentioned that the equal protection clause is the "sana all" doctrine under the Constitution. Section 1 of Article III (Bill of Rights) says: "No person shall be deprived of life, liberty, or property without due process of law, nor shall any person be denied the equal protection of the laws."

All persons or things similarly situated should be treated alike, both as to rights conferred and responsibilities imposed. Natural and juridical persons are entitled to this guarantee; but with respect to artificial persons, they enjoy the protection only insofar as their property is concerned. (Nachura)

The equal protection of the laws is embraced in the concept of due process, as every unfair discrimination offends the requirements of justice and fair play. It has nonetheless been embodied in a separate clause in Article III, Section 1 of the Constitution to provide for a more, specific guaranty against any form of undue favoritism or hostility from the government. Arbitrariness in general may be challenged on the basis of the due process clause. But if the particular act assailed partakes of an unwarranted partiality or prejudice, the sharper weapon to cut it down is the equal protection clause.According to a long line of decisions, equal protection simply 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 equal protection clause does not require the universal application of the laws on all persons or things without distinction. This might in fact sometimes result in unequal protection, as where, for example, a law prohibiting mature books to all persons, regardless of age, would benefit the morals of the youth but violate the liberty of adults. What the clause requires is equality among equals as determined according to a valid classification. By classification is meant the grouping of persons or things similar to each other in certain particulars and different from all others in these same particulars. (G.R. No. 105371. November 11, 1993)

Indeed, the equal protection clause permits classification. Such classification, however, to be valid must pass the test of reasonableness. The test has four requisites: (1) The classification rests on substantial distinctions; (2) It is germane to the purpose of the law; (3) It is not limited to existing conditions only; and (4) It applies equally to all members of the same class. "Superficial differences do not make for a valid classification." (G.R. No. 192531. November 12, 2014)

The meaning of the Equal Protection Clause has been the subject of much debate, and inspired the well-known phrase "Equal Justice Under Law." This clause was the basis for Brown v. Board of Education (1954), the Supreme Court decision that helped to dismantle racial segregation, and also the basis for many other decisions rejecting discrimination against, and bigotry towards, people belonging to various groups. While the Equal Protection Clause itself applies only to state and local governments, the Supreme Court held in Bolling v. Sharpe (1954) that the Due Process Clause of the Fifth Amendment nonetheless imposes various equal protection requirements on the federal government via reverse incorporation. https://en.wikipedia.org/wiki/Equal_Protection_Clause

Here is Pericles discussing "equal justice" according to the English translation by Richard Crawley in 1874: https://en.wikipedia.org/wiki/Equal_justice_under_law
Our constitution does not copy the laws of neighbouring states; we are rather a pattern to others than imitators ourselves. Its administration favours the many instead of the few; this is why it is called a democracy. If we look to the laws, they afford equal justice to all in their private differences; if no social standing, advancement in public life falls to reputation for capacity, class considerations not being allowed to interfere with merit; nor again does poverty bar the way, if a man is able to serve the state, he is not hindered by the obscurity of his condition.