Nor is it at all clear to me how the majority decides
which loaded “arms” a homeowner may keep. The majority
says that that Amendment protects those weapons
“typically possessed by law-abiding citizens for lawful
purposes.” Ante, at 53. This definition conveniently excludes
machineguns, but permits handguns, which the
majority describes as “the most popular weapon chosen by
Americans for self-defense in the home.” Ante, at 57; see
also ante, at 54–55. But what sense does this approach
make? According to the majority’s reasoning, if Congress
and the States lift restrictions on the possession and use of
machineguns, and people buy machineguns to protect
their homes, the Court will have to reverse course and find
that the Second Amendment does, in fact, protect the
individual self-defense-related right to possess a machinegun.
On the majority’s reasoning, if tomorrow someone
invents a particularly useful, highly dangerous selfdefense
weapon, Congress and the States had better ban it
immediately, for once it becomes popular Congress will no
longer possess the constitutional authority to do so. In
essence, the majority determines what regulations are
permissible by looking to see what existing regulations
permit. There is no basis for believing that the Framers
intended such circular reasoning.