A while ago I offered my thoughts on how the Court ought to decide the individual rights vs. collective rights dispute in Heller, concluding that the Second Amendment does indeed protect individual rights to keep and bear arms. (n1) Now, allow me to complete my pseudo-analysis of the case by discussing the substantive standards I believe the Court should apply to the District of Columbia's gun regulations and the conclusions the Court should reach about the constitutionality of those regulations.
I am not arrogant enough to pretend to offer a comprehensive and authoritative statement of the all the constitutionally-derived standards and rules that comprise the true legal meaning of the Second Amendment. However, I will be brave enough to set out a (very) rough and tentative framework for applying the Amendment. To put it directly: A gun regulation is constitutional under the Second Amendment if (1) it concerns firearms that are not similar in role to those in use at the time of the framing of the Amendment, (2) if it places limited and reasonable restrictions on the classes of people who can possess firearms, or (3) if it places reasonable restrictions on the purchase, storage, or carrying of firearms.
The first category of regulations mentioned survive scrutiny under the Second Amendment because they do not regulate "arms" within the meaning of the Amendment. Of course, the difficulty arises in determining which sorts of modern weapons are and are not "arms." The key to resolving this, I think, is to look to how firearms were used at the time of the framing. That is, we should inquire into the nature of an arm, as the Constitution uses the term. Firearms at the time of the framing were personal weapons: the squad-based highly portable machine guns of today, or even the Gatling Guns of the 19th century, had no equivalent. Moreover, when firearms were used -- whether for military purposes, for self-defense, or for hunting -- they were used (almost without exception) overtly: guns made to evade detection (such as plastic guns meant to undetected by metal detectors) or silenced weapons had no equivalent. On the other hand, the vast majority of modern pistols, rifles, and shotguns are fairly equivalent to their 1780's era predecessors in their personal nature and the functional overtness of their possession and use. Certainly, not all modern firearms can be so clearly classified in one category of another, but the "personal and overt" standard seems like a decent starting place for discerning what is a constitutionally-protected arm.
The second and third categories of permissible regulations are based upon implied exceptions to what constitutes "infringement" of the right to keep and bear arms under the Amendment. As was discussed in the Heller oral argument, in pre-framing Anglo-American law the right to possess arms was often denied to certain classes of people. The example of this that most immediately leaps to my mind is the limitation of the right to own arms in the English Bill of Rights to Protestants; in the immediate aftermath of the Glorious Revolution denying Catholic Englishmen the right to own arms was just fine by Parliament. More directly importantly for application of the Second Amendment, pre-enactment English law (as collected by Blackstone) assumed that government could make reasonably bar limited classes of people from owning arms without "infringing" on the general right to own arms. Thus, regulations that, for instance, prevent violent felons or the severely mental ill from owning firearms do not infringe on the constitutional right to possess arms. (n2)
The danger with recognizing the "certain classes of people" implied exception to the Second Amendment is the same with any implied exception: that the scope of the exception will be defined so broadly as to greatly shrink or essentially destroy the scope of the general right. One may answering this by offering that only "reasonable" class-of-owner limitations are constitutional. But of course "reasonable" is a term much abused in American law. I think a more useful formulation is that governments in the U.S. (n3) may implement narrowly tailored regulations to keep firearms from classes of persons who may be unusually likely, relative to the overall population, to use firearms to endanger themselves or others. The keys to that standard are the narrow tailoring requirement and the "unusually likely" provision; while governments may ban limited groups (such as felons or the insane) from owning firearms they may not prohibit vast swaths of population from owing arms based on a generalized public safety justification.
Finally, regulations are permissible under the Second Amendment if they reasonably restrict the purchase, storage, or carrying of arms. Here, we face some quite tough problems in applying the Second Amendment. The is little doubt from the pre-enactment history of Anglo-American law that governments imposed many and various restrictions on the how firearms could be acquired, kept, and used and that such restrictions were not viewed as infringing the general right to possess arms. Thus, we have another implied exception to the Second Amendment for such regulations, and also the problem of outlining that exception in a way that is sufficiently limited so as not to swallow the general right.
We may use "reasonableness" again, but again defining reasonableness is a problem. Indeed, it is much harder problem here that the one discussed above because of the vastly different kinds of firearm regulations that U.S. governments have imposed that fall within this third category. How, for instance, does one delineate a standard that can assess the reasonableness of both a prohibition against carrying concealed firearms in public places and a requirement that all gun owners store their firearms with trigger locks in place? The best answer to that, I think, begins from the recognition that imposing temporary delays or mild inconveniences on the possession of firearms is quite different from banning ownership of firearms. Governments do have legitimate interests in preventing gun accidents, protecting public safety, and the like, and regulations that pursue those aims without imposing a ban or de facto ban on the ownership of arms are permissible. Admittedly, this is an imperfect test. But probably about as good of one that can be applied to all of the types of "purchase, storage, carry" regulations that are out there. Moreover, remember that in undertaking analysis of particular gun regulations courts would be able to analogize to specific gun regulations that were clearly permitted or considered verboten in pre-Second Amendment Anglo-American as an interpretive aid.
With all of the above being said, we come to the validity of the actual gun regulations at issue in Heller: D.C.'s ban of the ownership of handguns and its requirement that rifles and shotguns either be stored with trigger locks in place or in a way that makes them immediately inoperable (eg. disassembled). I think both questions, assessed under the standards outlined above, are actually fairly easy. If the Second Amendment is to have any bite at all, a categorical ban on the possession of handguns cannot be considered a reasonable "purchase, storage, carry" regulation. On the other hand, from what I know of the trigger lock provisions in question I think they ought to be largely or entirely upheld. If indeed gun owners have the option of locking their weapons with inexpensive devices that can be removed in a matter of seconds it is difficult to see how that the requirement is equivalent to a de facto ban on ownership. In my view, the major difficulties the Court faces in Heller relate to beginning to discern the broad standards that should be applied in Second Amendment cases, not to actual application to the facts at hand.
It must be admitted, however, that many future cases brought under the Amendment will be pose problems that require more intensive parsing of facts. I am particularly thinking of cases addressing the validity of laws that prohibit possessing firearms that have certain types of functionality. The man-portable machine guns mentioned above are one example. As discussed, I'm sure these would not be considered arms within the meaning of the Second Amendment (and thus could be banned). But what about semi-automatic "assault rifles" (so-called) like those banned during the Clinton administration? What about, perhaps, even full automatic rifles? These would present closer questions than the D.C. regulations now at issue, and it will be very interesting to watch courts answer them. (n4)
For now, however, as the Chief Justice pointed out in the Heller argument perhaps we should stick at least somewhat close to addressing the case at hand. In the interest of not dragging this piece out any longer (and of not turning from offering tentative views to offering ill-though tout views) I shall leave it at that for now.
n1: I refer to "possession," "ownership," and "keeping and bearing" arms interchangeably here.
n2: This sort of implied exception to a right is recognized regarding many protections contained in our Bill of Rights (as was mentioned in the Heller argument, think of the implied exception for libel to the First Amendment's protections).
n3: I use "governments in the U.S." because although Heller only concerns federal regulations the protections contained in the Second Amendment will almost certain be incorporated to the states (and, by extension, localities) if the Court concludes in Heller that the Amendment offers has any significant force at all.
n4: Of course, the main reason that the Solicitor General does not fully support affirming the D.C. Circuit's opinion in the case is that the Administration fears that the lower court's reasoning, if entirely adopted by the Supreme Court, might call into question the validity of federal prohibitions against buying machine guns.