Are only light infantry weapons included? What about man-portable weapons? Does that include recoilless rifles?

How about improvised fighting vehicles? What about APCs or other armored vehicles? What about short-range missiles? Why not go unlimited (e.g. ICBMs)?!

Before addressing the verbs “keep” and “bear,” we interpret their object: “Arms.” The 18th-century meaning is no different from the meaning today. The 1773 edition of Samuel Johnson’s dictionary defined “arms” as “weapons of offence, or armour of defence.” 1 Dictionary of the English Language 107 (4th ed.) (hereinafter Johnson). Timothy Cunningham’s important 1771 legal dictionary defined “arms” as “any thing that a man wears for his defence, or takes into his hands, or useth in wrath to cast at or strike another.” 1 A New and Complete Law Dictionary (1771); see also N. Webster, American Dictionary of the English Language (1828) (reprinted 1989) (hereinafter Webster) (similar).

The term was applied, then as now, to weapons that were not specifically designed for military use and were not employed in a military capacity. For instance, Cunningham’s legal dictionary gave as an example of usage: “Servants and labourers shall use bows and arrows on Sundays, &c. and not bear other arms.” See also, e.g., An Act for the trial of Negroes, 1797 Del. Laws ch. XLIII, §6, p. 104, in 1 First Laws of the State of Delaware 102, 104 (J. Cushing ed. 1981 (pt. 1)); see generally State v. Duke, 42 Tex. 455, 458 (1874) (citing decisions of state courts construing “arms”). Although one founding-era thesaurus limited “arms” (as opposed to “weapons”) to “instruments of offence generally made use of in war,” even that source stated that all firearms constituted “arms.” 1 J. Trusler, The Distinction Between Words Esteemed Synonymous in the English Language 37 (1794) (emphasis added).

Some have made the argument, bordering on the frivolous, that only those arms in existence in the 18th century are protected by the Second Amendment. We do not interpret constitutional rights that way. Just as the First Amendment protects modern forms of communications, e.g., Reno v. American Civil Liberties Union, 521 U. S. 844, 849 (1997), and the Fourth Amendment applies to modern forms of search, e.g., Kyllo v. United States, 533 U. S. 27, 35–36 (2001), the Second Amendment extends, prima facie, to all instruments that constitute bearable arms, even those that were not in existence at the time of the founding.

Guns are just one category of “arms” that most Americans choose not to own or carry for self-defense, but guns alone saturate Second Amendment case law.

... According to some commentators, “the NRA is almost singlehandedly responsible for” bringing about the “now-dominant view” that the Second Amendment protects a personal right to arms for self-defense.⁸⁸

... Yet the Second Amendment does not mention “firearms,” but rather speaks of “arms.”⁹⁴ And though Heller was a gun case, the Court’s interpretation of the Second Amendment extended constitutional protection far beyond guns. Heller rejected the understanding—reflected in United States v. Miller (1939)—that the militia clause limits the scope of the Second Amendment.95 Rather, the Court held that the Second Amendment protects at its core an individual right centered around private self-defense.96 Consistent with that interpretation, the Court defined “arms” as any “[w]eapons of offence” or “thing that a man wears for his defence, or takes into his hands,” that is “carri[ed] . . . for the purpose of ‘offensive or defensive action.’”⁹⁷ The Court was unambiguous about the breadth of the term. “[T]he Second Amendment extends, prima facie, to all instruments that constitute bearable arms, even those that were not in existence at the time of the founding.” ⁹⁸ Put another way, the Second Amendment “guarantee[s] the individual right to possess and carry weapons in case of confrontation.” 99

To be sure, Heller did not say all “thing[s],” “instruments,” and “weapons” receive protection. The Court qualified that the Second Amendment is “not a right to keep and carry any weapon whatsoever in any manner whatsoever and for whatever purpose,”¹⁰⁰ but the Court articulated few exceptions to its broad definition. The Court “read Miller to say only that the Second Amendment does not protect those weapons not typically possessed by law-abiding citizens for lawful purposes,”¹⁰¹ which has led to a baseline inquiry of whether an arm is “in common use” for lawful purposes.¹⁰² The Supreme Court also said that “dangerous and unusual” weapons are not protected, but failed to explain what falls into that category other than “M-16 rifles and the like.”¹⁰³

Heller: It may be objected that if weapons that are most useful in military service—M-16 rifles and the like—may be banned, then the Second Amendment right is completely detached from the prefatory clause. But as we have said, the conception of the militia at the time of the Second Amendment’s ratification was the body of all citizens capable of military service, who would bring the sorts of lawful weapons that they possessed at home to militia duty. It may well be true today that a militia, to be as effective as militias in the 18th century, would require sophisticated arms that are highly unusual in society at large. Indeed, it may be true that no amount of small arms could be useful against modern-day bombers and tanks. But the fact that modern developments have limited the degree of fit between the prefatory clause and the protected right cannot change our interpretation of the right.

What weapons are included in the Second Amendment protections?