Some political scientists maintain that Supreme Court justices are more likely than other appellate court judges to vote their ideological preferences. It is argued that Supreme Court justices may vote their preferences without constraint from precedent because of a lack of electoral or political accountability, absence of ambition for higher office, and status as a member of a court of last resort that controls its own docket. While this expla nation of attitudinal voting is widely accepted, it has never been tested. As a first test of the asserted institutional foundations of attitudinal voting, the voting of United States Courts of Appeals judges in tort diversity cases is examined. In such cases, appeals court judges benefit from all of the institutional features thought to advance attitudinal voting, except complete docket control. Despite these benefits, the votes of the appeals court judges appear to be highly constrained by law and precedent.