Per Scalia in District of Columbia v. Heller: “Like most rights, the 2nd Amendment right is not unlimited. It is not a right to keep and carry any weapon whatsoever in any manner whatsoever and for whatever purpose: For example, concealed weapons prohibitions have been upheld...[and] the Court’s opinion should not be taken to cast doubt on longstanding prohibitions on the possession of firearms by felons and the mentally ill, or laws forbidding the carrying of firearms in sensitive places…or laws imposing conditions and qualifications on the commercial sale of arms.”

Setting the Tone: "He who knows only his own side of the case, knows little of that…Nor is it enough that he should hear the arguments of adversaries from his own teachers, presented as they   state them, and accompanied by what they offer as refutations. That is not the way to do justice to the arguments, or bring them into real contact with his own mind. He must be able to hear them from persons who actually believe them; who defend them in earnest, and do their very utmost for them. He must know them in their most plausible and persuasive form…." From: “On Liberty”, Collected Works of John Stuart Mill, Vol. XVII:   Essays on Politics and Society.