Stephen Choi (NYU), Mitu Gulati (Duke), and Eric Posner (Chicago), in What Do Federal District Judges Want? An Analysis of Publications, Citations, and Reversals, bring data to bear on the question of judge motives when it comes to opinion writing. From the abstract:
"We report evidence from a dataset of federal district judges from 2001 to 2002 that district judges adjust their opinion-writing practices to minimize their workload while maximizing their reputation and chance for elevation to a higher court. District judges in circuits with politically uniform circuit judges are better able to predict what opinions will get affirmed by the circuit court, leading to higher publication rates and a higher affirmance rate. In contrast, district judges in circuits with politically diverse circuit judges are less able to predict the preferences of the reviewing circuit court panel, leading district judges to publish fewer but higher quality opinions in an effort to maximize their affirmance rate."