The Constitution is a "living document". To conservatives that statement means that it is in force, the law of the land, rooted in the original meaning of the text. To liberals it means malleable and open to continuous re-interpretation to fit their their current opinions. Example: "well regulated militia". When written, it meant well trained, practiced, with arms that are maintained in good working order, ready to defend their communities if called upon. Many liberals think it means regulated by the government. Considering 2A was meant as a check on tyrannical government, that makes no sense.