Awhile back I posted about an article by Professor Oren Bracha entitled the "The Ideology of Authorship Revisited. " Professor Matthew Sag and his colleagues, Tonja Jacobi and Maxim Stych, have just posted on ssrn a paper entitled "The Effect of Judicial Ideology in Intellectual Property Cases," available here. Professor Sag et al have produced not a philosophical look at ideology as Professor Bracha did, but rather, a draft analysis of data from intellectual property cases decided in the U.S. Supreme Court from 1954 to 2006. They conclude that ideology "is a significant determinant of cases involving intellectual property rights. However, our analysis also shows that there are significant differences between intellectual property and other areas of law with respect to the effect of ideology." (Abstract).
As interestingly, within the IP field, they conclude that "compared to patent cases, in copyright cases, the justices were significantly less likely to vote against the IP owner, and conversely, were more significantly more likely to vote against the IP owner in trademark cases. One interpretation of this result is that the justices are more convinced by the incentive theory underlying copyright than they are by the consumer protection theory underlying trademark law. " (page 34).
This last conclusion is more easily susceptible of objective verification than the first conclusion about the effect of ideology (because you can see from the opinion who won or lost, appreciating that not all disputes are binary), but that shouldn't mean that efforts to discover whether ideology plays a role shouldn't be undertaken. The authors start from the premise of determining whether "copyright exceptionalism" -- the theory that copyright is not ideological in a political sense -- pans out. They note:
First, the Supreme Court decides an unusually large number of IP cases unanimously. Second, there are a number of IP cases in which justices vote against type, i.e. cases in which conservative justices vote against the IP owner or liberal justices vote in favor of the IP owner. Third, there are also many IP cases which produce strange coalitions of liberals and conservatives that would appear to defy the predictions of an attitudinal model.(page 17).
There are plenty of graphs and charts and explanations of models used, too detailed to go into here, and which address the expected objections to such an effort. A highly recommended read.