Antedating Heller v. District of Columbia by some years, the Cities of Chicago and Oak Park (each located in Illinois) had passed what were effectively bans on the private ownership of handguns within their respective jurisdictional boundaries. Subsequent to Heller, McDonald and co-plaintiff filed suit against those entities alleging the Cities actions violated the constitutional principles set forth in Heller, particularly the provisions of the Second and Fourteenth Amendments, and left plaintiffs vulnerable to criminals. Plaintiffs further sought declaratory judgment that the ban and several related ordinances violated constitutional provisions.
The District Court held that the Seventh Circuit Court of appeals had previously upheld the ordinances and ban in question and that Heller explicitly did not speak to whether the Second Amendment applied to the states and other subordinate non-Federal bodies. On appeal, the Seventh Circuit agreed with the District Court, relying on 19th Century precedent.
With Justice Alito writing for the majority, the Supreme Court of the United States reversed the decision of the lower courts regarding the case and sent the matter back to those lower courts to be re-decided taking into consideration the clarifying analysis provided by the Supreme Court in coming to a new decisions. That brings us to where we sit today.
Major issues in coming days appear to include:
1) Katrina style seizures of firearms from private citizens during a declared state of emergency would, under McDonald, appear to be an endangered range of activity.
2) Limitations on firearms owners posession of firearms - i.e., "one functional gun per household", mandatory insurance, barring guns outside of the gun owners home (even on the porch), etc remain to be settled. However, as a fundamental right (as described by SCOTUS in McDonald) it seems unlikely that most such harassment-motivated regulatory efforts will survive constitutional review.
3) Similarly, may-issue "subjective" ("Do I like you?" "Did you make a really nice donation to my campaign?" "Are you the right gender/color/religion?") concealed pistol and firearms licenses would appear vulnerable to litigation - since SCOTUS seems to indicate it will hold denial of Second Amendment Rights to the same standard as First Amendment rights...
4) Related to (3) some question exists about the entire notion of licensing a right, and SCOTUS seems to take exception to setting out any one section of the Bill of Rights for special and hostile treatment.
5) Some tests do exist, for instance the First Amendment "crying fire in a crowded theater" example of unprotected speech. What conduct under the Second Amendment might constitute similar conduct that might be acceptably regulated?
Heller, and subsequently McDonald, offer a bunch of good things - but a lot of questions that can only be answered in front of the Supreme Court are also raised, and must be resolved.