that the right to keep and bear arms was only guaranteed to the militia; but this would be an interpretation not warranted by the intent. The militia, as has been elsewhere explained, consists of those persons who, under the law, are liable to the performance of military duty, and are officered and enrolled for service when called upon. But the law may make provision for the enrolment of all who are fit to perform military duty, or of a small number only, or it may wholly omit to make any provision at all; and if the right were limited to those enrolled, the purpose of this guaranty might be defeated altogether by the action or neglect to act of the government it was meant to hold in check. The meaning of the provision undoubtedly is, that the people, from whom the militia must be taken, shall have the right to keep and bear arms; and they need no permission or regulation of law for the purpose. But this enables the government to have a well-regulated militia; for to bear arms implies something more than the mere keeping; it implies the learning to handle and use them in a way that makes those who keep them ready for their efficient use; in other words, it implies the right to meet for voluntary discipline in arms, observing in doing so the laws of public order. Commentary since late 20th century Until the late 20th century, there was little scholarly commentary of the Second Amendment. In the latter half of the 20th century, there was considerable debate over whether the Second Amendment protected an individual right or a collective right. The debate centered on whether the prefatory clause ("A well regulated militia being necessary to the security of a free State") declared the amendment's only purpose or merely announced a purpose to introduce the operative clause ("the right of the People to keep and bear arms shall not be infringed"). Scholars advanced three competing theoretical models for how the prefatory clause should be interpreted. The first, known as the "states' rights" or "collective right" model, held that the Second Amendment does not apply to individuals; rather, it recognizes the right of each state to arm its militia. Under this approach, citizens "have no right to keep or bear arms, but the states have a collective right to have the National Guard". Advocates of