Are apex court judges politically biased?

The question whether judges are politically biased is highly disputed. Some consider it a heresy even to ask the question, while others believe it to be a self-evident truism. If we look at how controversial the nomination procedures for new justices to the U.S. Supreme Court are, we see that most participants in the U.S. political process at least believe that justices are influenced by their political ideology. There is some empirical evidence confirming this belief. The seminal contribution on this issue is a study by Jeffrey Segal and Albert Cover. The authors construct an ideology score for Supreme Court Justices, which is based on newspaper reports regarding these judges prior to their election to the Court. The study finds a high correlation between...