A common misconception about the Second Amendment is that it only protects arms for the militia, or in modern day, the National Guard or other government-organized military group. This is simply untrue; a belief arising from ignorance about the language used in the Second Amendment and understanding its meaning as it was understood originally when the Bill of Rights was ratified. Fortunately, the Supreme Court helps us understand the original intent of the Second Amendment and the words used in their historical context.
In the landmark Supreme Court case, D.C. vs Heller, the court explains that all citizens are the militia; the Second Amendment is an individual right, just like every other right protected in the Bill of Rights, and is independent of membership in any organized group or military unit.
The Second Amendment reads: “A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed.”
There are two clauses that comprise the Second Amendment, an operative clause, and a prefatory clause.
Operative clause: "The right of the people to keep and bear Arms, shall not be infringed."
The operative clause is the actual protected right; kind of the 'meat and potatoes.' The court wrote: "1. Operative Clause. a. 'Right of the People.' [used 3 times in Bill of Rights] ... All three of these instances unambiguously refer to individual rights, not 'collective' rights, or rights that may be exercised only through participation in some corporate body." (p.5).
Prefatory clause: "A well regulated Militia, being necessary to the security of a free State."
The prefatory clause is the lead-in that “announces a purpose” for the operative clause. The court stated: "The Amendment’s prefatory clause announces a purpose, but does not limit or expand the scope of the second part, the operative clause. The operative clause’s text and history demonstrate that it connotes an individual right to keep and bear arms"(Heller law syllabus p.1).
The court also stated: "The Amendment could be rephrased, 'Because a well regulated Militia is necessary to the security of a free State, the right of the people to keep and bear Arms shall not be infringed.'” (Heller law syllabus p.3, emphasis added).
Note: “syllabus” in law briefs is not like a college course summary, but “a short note preceding the text of a reported case that briefly summarizes the rulings of the court on the points decided in the case."
The Militia is all of the people
The court states: "It was clearly an individual right, having nothing whatever to do with service in a militia" (p.20), adding "Reading the Second Amendment as protecting only the right to “keep and bear Arms” in an organized militia therefore fits poorly with the operative clause’s description of the holder of that right as “the people” (p.7).
It's clear from the court's ruling regarding the relationship between the prefatory and operative clause (p.25) that the militia meant that all of the people were armed.
“The 'militia' comprised all males physically capable of acting in concert for the common defense. The Anti-federalists feared that the federal government would disarm the people in order to disable this citizens’ militia, enabling a politicized standing army or a select militia to rule. The response was to deny Congress power to abridge the ancient right of individuals to keep and bear arms, so that the ideal of a citizens’ militia would be preserved” (Heller law syllabus, p.2, emphasis added).
“Keep arms” was simply a common way of referring to possessing arms, for militiamen and everyone else" (p.9).
Congress creates the Army and Navy, but not the already existent militia
The court states that while Congress is given the power in Article I of the Constitution to create the Army and the Navy, it may simply organize the militia because it already existed:
"Unlike armies and navies, which Congress is given the power to create, the militia is assumed by Article I already to be in existence. Congress is given the power ... to organize “the” militia, connoting a body already in existence," (p.23).
Second Amendment doesn't mean any organized military unit
We find on page 11: "In numerous instances, 'bear arms' was unambiguously used to refer to the carrying of weapons outside of an organized militia," adding further that, "It is clear from those formulations that 'bear arms' did not refer only to carrying a weapon in an organized military unit" (p.11-12). Fun fact: The National Guard, as it exists today, wasn't created until 1903.
So we see that at the time of its writing, it was clearly understood that the Second Amendment protected the right of all citizenry to have and carry arms. Our ignorance of the terminology, and perhaps the phrasing of the two clauses has clouded this truth, so obvious to our Founders. The Second Amendment means all of us, since we are all since we are all the militia, and in no way means only an organized military unit or the National Guard.