(snip ... ) Justice Antonin Scalia's majority opinion in Heller noted that, because the plaintiffs "conceded at oral argument" that they do not "have a problem with... licensing," the court would "not address the licensing requirement." The appeals court in that case did, however, and suggested that registration was just fine: "Reasonable restrictions also might be thought consistent with a 'well regulated militia.' The registration of firearms gives the government information as to how many people would be armed for militia service if called up."
At this point it's probably helpful to look at the actual text of the Second Amendment, which reads: "A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed."
In legal circles, there's a never-ending (more like all-consuming) debate about how to interpret such language. To oversimplify: Some conservative justices, including Scalia, tend to look to the original meaning of the words in ordinary use at the time it was written. Others argue for the concept of a "living Constitution," meaning the Constitution is dynamic and should evolve over time to reflect evolving social values.
You can figure out for yourself which school of thought ended up on which side in last year's 5-4 Heller decision.
The problem for gun rights advocates is that, if you look at the language and custom at the time the Second Amendment was written, laws like the Militia Act of 1792 pop up. It required men between the ages of 18 and 45 to register themselves for militia service, and specified they have certain weapons such as a "good rifle." Similarly, a report from Philadelphia in 1823 showed that there were 12,678 rifles in private hands, indicating some records of who owned what.
"Systems akin to registration were quite common at the time of the framing of the Constitution and the time of the ratification of the Bill of Rights," says Dennis Henigan, vice president for law and policy at the Brady Campaign and author of the new book Lethal Logic. "Even before that the state militia statutes had the same kind of requirements, so they can track how well the militia was armed."
Sorry, Mandatory Gun Registration Is Constitutional - Taking Liberties - CBS News