McDonald v. Chicago did nothing to clarify the nature of permissible gun regulations. The Court merely reaffirmed the holding in Heller that “longstanding prohibitions” and bans in “sensitive places” are still permisisble. Unfortunately, we learn nothing new about the types of gun control regulations that are constitutional.

From the Majority opinion:

It is important to keep in mind that Heller, while striking down a law that prohibited the possession of handguns in the home, recog-nized that the right to keep and bear arms is not “a right to keep and carry any weapon whatsoever in any manner whatsoever and for whatever purpose.” 554 U. S., at ___ (slip op., at 54). We made it clear in Heller that our hold-ing did not cast doubt on such longstanding regulatorymeasures as “prohibitions on the possession of firearms by felons and the mentally ill,” “laws forbidding the carrying of firearms in sensitive places such as schools and gov-ernment buildings, or laws imposing conditions and quali-fications on the commercial sale of arms.” Id., at ___–___ (slip op., at 54–55). We repeat those assurances here.Despite municipal respondents’ doomsday proclamations, incorporation does not imperil every law regulating firearms.

The court reitierated that the core of the right to keep and bear arms was the right of self-defense, reaffirming the Heller holding.

In Heller, we recognized thatthe codification of this right was prompted by fear that the Federal Government would disarm and thus disable the militias, but we rejected the suggestion that the right was valued only as a means of preserving the militias. 554
U. S., at ___ (slip op., at 26). On the contrary, we stressedthat the right was also valued because the possession offirearms was thought to be essential for self-defense. As we put it, self-defense was “the central component of the right itself.” Ibid.

…

In Heller, we recognized thatthe codification of this right was prompted by fear that the Federal Government would disarm and thus disable the militias, but we rejected the suggestion that the right was valued only as a means of preserving the militias. 554
U. S., at ___ (slip op., at 26). On the contrary, we stressedthat the right was also valued because the possession offirearms was thought to be essential for self-defense. As we put it, self-defense was “the central component of the right itself.” Ibid.

Justice Breyer takes this standard to task, and argues that the sensitive places and longstanding prohibition rules are “haphazard.”

Rather, the Court has haphazardly created a few simple rules, such as that it will not touch “prohibitions on the possession of firearms by felons and the mentally ill,” “laws forbidding the carrying of firearms in sensitive places such as schools and government buildings,” or “laws imposing conditions and qualifications on the commercial sale of arms.” Heller, 544 U. S., at ___ (slip op., at 54–55); Ante, at 39 (plurality opinion). But why these rules and not others? Does the Court know that these regulations are justified by some special gun-related risk of death? In fact, the Court does not know. It has simply invented rules that sound sensible without being able to explain why or how Chicago’s handgun ban is different.

Paraphrasing Chief Justice Roberts’ opinion in Caperton, Breyer poses 24 consecutive hypothetical questions–though the Chief asked 40!

Given the competing interests, courts will have to try toanswer empirical questions of a particularly difficult kind.Suppose, for example, that after a gun regulation’s adoption the murder rate went up. Without the gun regulationwould the murder rate have risen even faster? How is this conclusion affected by the local recession which has left numerous people unemployed? What about budget cutsthat led to a downsizing of the police force? How effective was that police force to begin with? And did the regulation simply take guns from those who use them for lawfulpurposes without affecting their possession by criminals?
Consider too that countless gun regulations of manyshapes and sizes are in place in every State and in manylocal communities. Does the right to possess weapons forself-defense extend outside the home? To the car? To work? What sort of guns are necessary for self-defense?Handguns? Rifles? Semiautomatic weapons? When is a gun semi-automatic? Where are different kinds of weapons likely needed? Does time-of-day matter? Does the presence of a child in the house matter? Does the presence of a convicted felon in the house matter? Do police need special rules permitting patdowns designed to findguns? When do registration requirements become severe to the point that they amount to an unconstitutional ban?Who can possess guns and of what kind? Aliens? Prior drug offenders? Prior alcohol abusers? How would the right interact with a state or local government’s ability totake special measures during, say, national security emergencies? As the questions suggest, state and local gunregulation can become highly complex, and these “are onlya few uncertainties that quickly come to mind.” Caperton
v. A. T. Massey Coal Co., 556 U. S. ___, ___ (2009) (ROB-ERTS, C. J., dissenting) (slip op., at 10).