Alli has a good post up about Judicial Philosophy. I too am disturbed about the push for a "Conservative" or "Liberal" judge. I want someone who will base their decision on the law, in the case of the Supreme Court, on the Constitution.
When I was in college, I spent a considerable amount of time on the study of History. I especially enjoyed those classes that focused on the study of historians. I spent a fair amount of time studying historians and their approach to history. You might tell me that a fact is a fact, history is what it is. I would disagree. Let us say in 49 BC Julius crossed a small river in northern Italy. He was on his way to market. Do we care? Is that history? What if he had a group of friends with him? Is that change your answer? The "fact" that 10 minutes later another guy named Julius (Caesar) crossed that same river, the Rubicon, is of great importance to us. The Roman Civil War, the Roman Empire, our Christian religion, our very language and culture are influenced by this single act. As a historian we have to look at episodes and actions in history to determine what "facts" are important.
Then we have to deal with our biases. If we are a supporter of Caesar the crossing of the Rubicon is a good thing. Let us look a little closer to home. For many of us, the overthrow of Saddam Hussein was a good thing. Even most of the anti-war crowd agree on this "fact". What if you were one of the elites in Iraq, a member of the ruling bureaucracy or a family member of such? Your take on the situation would be a little different. We all have biases. To the extent we can overcome those biases tells us how good historians or judges we can be. As you tell your grandchildren what it was like to be alive in the 1940s, or the 1960's you bring a set of biases to the table. American, British, French, and Russians of the era will have a different version of what happened in the 1930s and 1940s than a German or Japanese. Your position on Vietnam will color your perspective of the 1960s anti-war movement.
When we consider a Supreme Court Justice, many of us are looking for a strict Constitutionalist. We want a judge who does not see privacy rights in the commerce clause. A judge that does not consider the case law of Canada, Estonia, or Uzbekistan when deciding US Constitutional law. No matter how hard the Justice tries, he will bring his biases, his learning, his unique view of life with him. The degree that he can separate his personal beliefs from the Law, determines his place in history.
The ability to separate the law from personal beliefs, can a Catholic judge rule on cases involving Masons? Can a judge of African decent rule on the rights of the KKK to march? Did he rule in favor of the NRA, even though he finds guns loathsome? That is what Congress should look at when giving their "advise and consent". Look at the body of work: as a judge did the candidate rule fairly? Did he try to interpret the law in the strictest possible sense? Those questions are far more important than a man's religious or personal beliefs.