Of course, the qualification, experience, and decision making capabilities are also analyzed and form an integral part of the appointment process.
Almost everyone would maintain that the appointment of Supreme Court Judges should not be made using the above criteria as this violates the principles of independence. A Supreme Court is the highest judicial bench in the country and as such, the decisions should be taken on merit; without prejudice to any person, belief, or religion; and after careful analysis of all evidences. However, if the appointments are made based on personal preferences, the decisions may be skewed towards the state and according to the desires of President's office. This creates the controversy that Supreme Court is not as independent as one would like it to be.
'''The biggest damn fool mistake I ever made,'' Dwight D. Eisenhower said of his appointment of Chief Justice Earl Warren, who discomfited him with the Brown v. Board of Education ruling ordering desegregation of public schools, and other liberal opinions. Harry S. Truman was even more scathing about Justice Tom C. Clark, a Truman appointee who voted against his 1952 seizure of the steel industry to avert a strike.' (Purdum 2005).
This shows that the Court decisions are not always biased in favor of ...