Recently, the majority on a divided three-judge panel of the U.S. Court of Appeals for the D.C. Circuit issued the first-ever federal appellate court ruling that invalidated a gun control law based on the so-called "individual right" interpretation of the Second Amendment to the U.S. Constitution.
Because other federal appellate courts have rejected the "individual right" understanding in favor of a so-called "collective right" view essentially limiting the Second Amendment's protections to organized militias, many commentators have remarked that U.S. Supreme Court review of the D.C. Circuit's ruling is almost certain to occur.
But even if the Supreme Court agrees to hear the case, there remains a potentially significant obstacle that may prevent the justices from using the case to resolve whether the "individual right" or "collective right" view of the Second Amendment is proper. The obstacle, which is the central focus of D.C. Circuit Judge Karen LeCraft Henderson's dissenting opinion, is that the Second Amendment may not apply to the District of Columbia.
Details here from Howard Bashman via Law.com. The D.C. Circuit's opinion is Parker v. District of Columbia.