Those interested in the growing empirical literature on judicial decisionmaking will want to read a thoughtful paper by Brian Tamanaha (St. John's). The Distorting Slant of Quantitative Studies of Judging develops two main points:
"The first point is that the field was born in a collection of false beliefs and misunderstandings about the formalists and the realists which has distorted how political scientists have modeled judging and how they have designed and interpreted their studies. Rather than conduct an open inquiry into the nature of judging, political scientists set out to debunk formalism by proving that judging is infused with politics, a mission that warped the development of the field.
The second point is that the results of their studies below the Supreme Court strongly confirm what judges have been saying for many decades - that their judicial decisions are substantially determined by the law. Political scientists have tended to repress this finding, however, by focusing on the wrong point: repeating time and again that their studies show that politics matters without also emphasizing that it matters very little. A balanced realism about judging accepts that - owing to the uncertainty of law and the inherent limitations of human decision makers - it is inevitable that there will be a certain (minimal) degree of political influence in judicial decision making, but this does not detract from the broader claim that judges can and usually do rule in accordance with the law."