Richard Briffault has posted Defining the Constitutional Question in Partisan Gerrymandering (forthcoming in the Cornell Journal of Law and Public Policy symposium on Vieth v. Jubelirer). Here is the abstract:

In Vieth v. Jubelirer, a narrow majority of the Supreme Court determined that, at least for the moment, partisan gerrymandering is nonjusticiable. Yet, strikingly, all nine members of the Court also agreed that, justiciable or not, partisan gerrymanders raise a constitutional question, and some gerrymanders are unconstitutional. However, the Court gave little attention to just why gerrymandering might be unconstitutional.
The justices bounced back and forth between justiciability and the standards for proving gerrymandering without considering what constitutional harm gerrymandering poses.
This Article considers the question of why partisan gerrymandering might be unconstitutional. It finds four
constitutional arguments against gerrymandering in judicial opinions and the academic literature: (i) vote dilution in
violation of the equal protection clause; (ii) burdening of political association in violation of the first amendment; (iii)
frustration of the competitiveness necessary for democratic elections; and (iv) excessive pursuit of partisan or individual legislator self-interest.
The Article contends that the first three arguments are likely to fail, in part because the theories they rely on are ultimately in tension with the use of districting to elect legislators. The fourth argument comes closest to capturing the constitutional harm posed by gerrymandering while remaining consistent with the use of districting. Of course, the fourth argument implicates the manageability concern that gives force to the argument against justiciability. Yet, the experience with Shaw v. Reno claims alleging excessive use of race in districting, suggests that the excessive partisanship/self-interest theory of partisan gerrymandering may also be judicially manageable – if the Court concludes that the harm posed by gerrymandering is serious enough to justify judicial intervention.