Today, the Supreme Court will hear oral arguments in the case of Heller v. District of Columbia, a suit brought by several D.C. citizens contending that the ban on the possession of operable firearms inside one's home violates the Second Amendment. The Circuit Court of Appeals for D.C. agreed and held the ban to be unconstitutional. However it is decided, Heller is already historic. For the first time in recent memory, the Supreme Court will consider the original meaning of a significant passage of the Constitution unencumbered by its own prior decisions. The majority and dissenting opinions in this case will be taught in law schools for years to come. Here's a layman's guide to the significance of the case:

- Heller will be decided on originalist grounds. Among law professors, enforcing the original meaning of the Constitution is highly controversial. Critics of originalism deny that we should be ruled by the "dead hand of the past." They prefer following Supreme Court precedents that may or may not be consistent with original meaning. Any justice who today professes a commitment to originalism is branded a radical; and all Supreme Court nominees are now grilled on their commitment to the doctrine of stare decisis. But what are old precedents if not the "dead hand" of dead justices?

Significantly, then, both sides in Heller are making only originalist arguments. The challengers of the law contend that the original meaning of the Second Amendment protects an individual "right to keep and bear arms" that "shall not be infringed." In response, the District does not contend that this right is outmoded and that the Second Amendment should now be reinterpreted in light of changing social conditions. Not at all. It contends instead that, because the original intention of the Framers of the Second Amendment was to protect the continued existence of "a well regulated militia," the right it protects was limited to the militia context.

So one thing is certain. Whoever prevails, Heller will be an originalist decision. This shows that originalism remains the proper method of identifying the meaning of the Constitution.

- The Second Amendment protects an individual right. In the 1960s, gun control advocates dismissed the Second Amendment as protecting the so-called "collective right" of states to preserve their militias -- notwithstanding that, everywhere else in the Constitution, a "right" of "the people" refers to an individual right of persons, and the 10th Amendment expressly distinguishes between "the people" and "the states." Now even the District asserts the new theory that, while this right is individual, it is "conditioned" on a citizen being an active participant in an organized militia. Therefore, whoever wins, Heller won't be based on a "collective" right of the states.