Meaning of "keep and bear arms"
In Heller the majority rejected the view that the term "to bear arms" implies only the military use of arms:
Before addressing the verbs "keep" and "bear," we interpret their object: "Arms."
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. Thus, the most natural reading of "keep Arms" in the Second Amendment is to "have weapons." At the time of the founding, as now, to "bear" meant to "carry." In numerous instances, "bear arms" was unambiguously used to refer to the carrying of weapons outside of an organized militia. Nine state constitutional provisions written in the 18th century or the first two decades of the 19th, which enshrined a right of citizens "bear arms in defense of themselves and the state" again, in the most analogous linguistic context—that "bear arms" was not limited to the carrying of arms in a militia. The phrase "bear Arms" also had at the time of the founding an idiomatic meaning that was significantly different from its natural meaning: "to serve as a soldier, do military service, fight" or "to wage war." But it unequivocally bore that idiomatic meaning only when followed by the preposition "against,". Every example given by petitioners’ amici for the idiomatic meaning of "bear arms" from the founding period either includes the preposition "against" or is not clearly idiomatic. In any event, the meaning of "bear arms" that petitioners and Justice Stevens propose is not even the (sometimes) idiomatic meaning. Rather, they manufacture a hybrid definition, whereby "bear arms" connotes the actual carrying of arms (and therefore is not really an idiom) but only in the service of an organized militia. No dictionary has ever adopted that definition, and we have been apprised of no source that indicates that it carried that meaning at the time of the founding. Worse still, the phrase "keep and bear Arms" would be incoherent. The word "Arms" would have two different meanings at once: "weapons" (as the object of "keep") and (as the object of "bear") one-half of an idiom. It would be rather like saying "He filled and kicked the bucket" to mean "He filled the bucket and died."[164]
In a dissent, joined by Justices Souter, Ginsburg, and Breyer, Justice Stevens said:
The Amendment's text does justify a different limitation: the "right to keep and bear arms" protects only a right to possess and use firearms in connection with service in a state-organized militia. Had the Framers wished to expand the meaning of the phrase "bear arms" to encompass civilian possession and use, they could have done so by the addition of phrases such as "for the defense of themselves".[168]