Points of law
“The Equal Protection Clause prohibits a State from "deny[ing] to any person within its jurisdiction the equal protection of the laws." Amdt. 14, § 1.” Evenwel v. Abbott, 578 U.S. 54, 76 (2016)
It does, indeed: "No State shall […] deny to any person within its jurisdiction the equal protection of the laws." (U.S. Const. Amdt. 14, § 1.)
Research and axiomatic foundations
Many of the particular rules and federal decisional laws deriving from the Equal Protection Clause follow this principle; however, I have not been able to locate a formulation of it such that would declare it as a matter of law binding the federal government, and not just one state or another.
For this reason, I believed this might have been one of ""those settled usages and modes of proceeding" found in the common law[; (Murray's Lessee v. Hoboken Land & Improvement Co., 18 How. 272, 277 (1856)) … or ancient rules" (Wooden v. United States (Mar. 7, 2022, No. 20-5279) [pp. 33-34]) conserved and provided under the Fifth Amendment in the meaning of the Due Process of Law.
For this reason, I looked at parallel legal systems into which the same ancient European ancestor divided into in hope to find an ancient latin sobriquet that would be used so and potentially carry similar meaning under U.S. jurisprudence.
The continental (and now British) jurisprudential principle of the "equality of arms" provides that the integruos or decent process of law requires that "the prosecution and the defence have equal opportunity and opportunity to express their views and positions on questions of fact and law in criminal proceedings [… under] Article 6(3) of the [European Convention of Human Rights ("ECHR")] […] and "ECtHR considers all non-criminal proceedings as civil proceedings for the purposes of Article 6, [(incl. of 'fair trial' in Article 6(1))] it should be borne in mind that the category established by the ECtHR includes administrative proceedings in addition to civil proceedings in the constitutional sense, where the requirement of equality of arms must also be satisfied." (Erzsébet A. Gácsi, The principle of equality of arms the case law of the European Court of Human Rights, 2007, DeepL translation)
I found no Latin cognate of the "equality of arms", and I failed to find it explicitly named under U.S. jurisprudence; hence, my own research ended there, and my question began here:
Can an argument be made that the federal government is not also bound by the same principle expressed here, in other words, can an argument be made that: The Federal government may deny to any person within its jurisdiction the equal protection of the laws.
Accordingly, could an argument be made that the federal government is not subject to the provisions or any subsequent decisional-law formulation of the U.S. Constitution requiring that "all persons similarly circumstanced … be treated alike" (Plyler v. Doe, 457 U.S. 202, 216 (1982)) including by the United States?
Or even better, was there ever any binding argument made to such effect?