I start with Kopel, The Natural Right of Self-Defense - Heller's Lesson for the World (Syracuse Law Review, 2008).

Kopel primarily looks to "natural law" in this article, but also deals with some statutory law - e.g., the 1689 English Declaration of Rights (aka "English Bill of Rights"; actually a Royal-Parliament Compact). That important document (a partial model for the Declaration of Independence) was interpreted differently in the UK and the "US" prior to the American Revolution. That divergence has only increased after that; not only re: gun control, but also with respect to the limitations of legislative power.

The American interpretation re: self-defense speaks of "right", not "privilege". E.g., Kopel, p.5, from Gray v. Combs, 30 Ky. (7 J.J. Marsh) 478, 481 (Ky. 1832):

... the right of necessary defence, in the protection of a man’s person or property, is derived to him from the law of nature, and should never be unnecessarily restrained by municipal regulation. However proper it may be for every well ordered community to be tender of the public peace, and careful of the lives of its citizens, there can be neither policy or propriety in extending this tenderness and care so far as to protect the robber, the burglar and the nocturnal thief, by an unnecessary restraint of the honest citizen’s natural right of self-defence.

Sir Matthew Hale, in speaking on this subject, says, “the right of self-defence in these cases is founded in the law of nature, and is not, nor can be superceded by the law of society. Before societies were formed, the right of self defence resided in individuals, and since, in cases of necessity, individuals incorporated into society, can not resort for protection to the law of society, that law with great propriety and strict justice considereth them as still, in that instance, under the protection of the law of nature.”
In our "modern" times, "cases of necessity" are easy enough to find.

However, Kopel's view is certainly contested by Vera Bergelson, Professor of Law and Robert E. Knowlton Scholar, whose background is:

Professor Bergelson earned her diploma in Slavic languages and literatures with distinction from Moscow State University and her Ph.D. in philology from the Institute of Slavic and Balkan Studies in Moscow, Russia. She earned her J.D. cum laude from the University of Pennsylvania Law School, where she was on the Law Review and was named to the Order of the Coif.

Professor Bergelson has been a lecturer at Moscow State University, the Polish Cultural Center, and the Literary Institute in Moscow. Before joining the Rutgers faculty in 2001, she was an associate with Cleary, Gottlieb, Steen & Hamilton in New York for six years. She is fluent in Russian and Polish and has a reading proficiency in Bulgarian, Belorussian, and Ukranian.
Ms Bergelson is well-rooted in Russian jurisprudence, which is not close to that of the US.

Kopel quotes her at p.13n.55:

All public officials - a policeman performing a valid arrest, a sheriff taking possession of the debtor’s property pursuant to a court judgment, or an executioner giving the prisoner a lethal injection in accordance with the execution order - act under the right to act that way. In contrast, people acting in self-defense, or pursuant to necessity or parental authority, act merely under a privilege.
Needless to say, police states anywhere in the World are happy enough to see that public officials act as a matter of right, and that their people act as a matter of privilege. One should recall Dr Zhivago's rebuke: "That law gives you the power, not the right."

As we shall soon see, Ms. Bergelson's view is one shared by the UN and most (all ?) European countries.

cont. in pt. 2