Charles Evans Hughes, a former Supreme Court Chief Justice, once commented that the Constitution means whatever the Supreme Court says that it means. By exercising the right of Judicial Review, the courts have at times expanded the powers of Congress but at other times have hampered that power. This would not present a problem except for the fact that this very interpretation often varies with the composition of the Court. Congress is, therefore, somewhat hostage to the will of the Court and its several members.
The great challenge faced by the Supreme Court as it attempts to interpret how to apply the Constitution to changing times lies in the fact that not everyone agrees on what that interpretation means. Those who agree with any given Supreme Court decision will applaud the justices and their ability to apply the "living document" that is the Constitution wisely and objectively to changing circumstances and situations that were unforeseen by the writers of the Constitution. Those who disagree with a decision object vigorously, claiming that the justices are rewriting the law through their interpretation of the Constitution. The system of checks and balances and the separation of powers between the branches of the government don't eliminate the conflicts between different parts of the government or between members of the public with conflicting points of view.
I think the Constitution has to be thought of as a living document that is able to adapt to a changing world. As far as who should be responsible for how it changes and adapts to the changes I think you have to look at the three branches of government and how they work together to keep one branch from having too much power.
I think one of the strengths of the American political system is the way that its constitution can be treated not as an inflexible and rigid set of 10 commandments that are set in stone, but can actually be interpreted and viewed as a "living document" as history marches on and situations and contexts change dramatically. Of course, the problem lies in the way in which some would argue that the role of the nine in carrying out this job is not actually done impartially. Of course, as #5 points out, any true objectivity is something of a myth, and we find it impossible to make such big decisions without our own personal biases coming into play, but at the same time, we need to remember the kind of people that the nine are and the experience and training they have had.
Some people claim that thinking of the constitution as a "living document" turns judges into lawmakers rather than making them interpreters of laws (or at least of legal principles) that have existed for hundreds of years. Being a maker of laws is obviously a tempting role for judges, often for the best of motives; whether it is a proper role for judges is another question. Those who resist a legislative role for judges believe that it is important for judges to try to be as objective, impartial, and nonpolitical as possible. Whether these are impossible ideals is, of course, yet another question. :-) No wonder this is such an intriguing topic of discussion and debate!
This is an interesting question and one that Supreme Court Justice Oliver Wendall Holmes thought much about as is revealed in his biographies and letters to Sir Frederick Pollack. Perhaps an illustration from Holmes ideology will serve to add some clarity. Holmes asserted that his roll was to determine if laws upheld the Constitution or violated it. Since he held this view, he on occasion was forced to uphold laws that he personally disagreed with and would have liked to see struck down but which were not in contradiction to nor in violation of the Constitution. His belief was that this way was the only way to be true to the aim of the Supreme Court and avoid usurping legislative power from the Congresses to the Supreme Court. His aim was to avoid "legislating from the bench."
This example can be used either for or against in questioning the "living document" theory. It begs the question of whether Holmes, in light of his aim, may or may not have found that, for example, Civil Rights legislation did or did not uphold the Constitution. If one can prove an indication that perhaps Holmes might have found that Civil Rights violates the Constitution, then you may have a strong argument for a more flexible interpretation, a "living" interpretation, based on the overall social structure of the given day. If, on the other hand, one might prove an indication that Holmes might have found in favor of Civil Rights, then therein lies an argument for the sufficiency of the aim of avoiding "legislation from the bench."
To argue for this point of view, think about the implications of simply allowing the Constitution to be "alive." If you take this to its logical conclusion, what is to prevent judges from simply making the Constitution mean whatever they want?
Think, for example, about the idea of finding a right to privacy in the Constitution. This has led to the Supreme Court taking positions that the people who wrote the Constitution would surely never have contemplated. I am referring here to the ruling that abortion (in the first trimester) cannot be banned and to the idea that homosexual acts are protected by the Constitution.
What (you might ask) is the point of having a written Constitution if its meaning can be changed at the whim of judges? Should we not stick to the meaning of the document as written? If we want it to be changed, we are able to change it through the use of amendments. That would allow the Constitution to "live" without running into the problem of having judicial activism usurp the powers of the legislative branch.
So, I would focus on this idea -- that a written Constitution means nothing if it can be changed based on judges' opinions as to how the values of society have changed. If societal values have truly changed, let that be reflected by amendments and by laws, not by the choices of judges.
Please note that I'm not trying to deny the validity of your points. I'm actually just trying to show you the other side so that you can explain it regardless of what you or I might believe.
I agree with you in that the Constitution being "alive" and flexible in interpretation over time has been exactly what has allowed our government to successfully use it as a set of governing principles for more than two centuries, as it allows it to more accurately reflect the social and political values of the country in the current time frame.
Legislating from the bench, or "judicial activism" is a common complaint against the Court, but I find it most often used in the context of a decision someone disagrees with. It's quite a logical disconnect to argue that because a decision of nine Constitutional scholars goes against an individual's philosophy, it is an "activist" decision.
I think your understanding of the concept and your applying modern political and social realities to that concept (as well as the excellent questions you are asking yourself) shows that you are on the right track. While it is often inconvenient and difficult to take positions you don't necessarily agree with, it forces you to analyze opposing arguments you may never have considered otherwise. As your own philosophies develop and shift over the course of your education and life, I think you'll find, as I did, that nothing clarifies principle faster than being forced to critique and defend it on a regular basis. Keep up the good work.