Political Ideology and the Constitutionality of Campaign Finance Reform:
One of the interesting aspects about the constitutional debate over campaign finance reform is that conservatives tend to think it's unconstitutional while liberals tend to think it's lawful. It's interesting to step back and ask, why is that?

  As best I can tell, constitutional theory doesn't provide an answer. Both sides seem to make their arguments using modern cases and policy arguments. Even when self-proclaimed originalist like Justice Scalia and Justice Thomas write opinions explaining votes to strike down campaign finance laws, they generally gloss over the history pretty quickly before focusing on modern court-made legal doctrine (see, e.g., here and here).

  My best guess is that the legal positions polarize as they do for two reasons. The first is that the constitutional questions are genuinely hard. The doctrine as it comes to us is unusually murky, and there are reasonable arguments on both sides. Murky precedents and good arguments on both sides tend to trigger ideological divisions: The less traditional legal arguments provide clear answers, the more judges are likely to gravitate to their political views.

  That brings me to the second point, that the politics of campaign finance are pretty polarized. For the most part, conservatives have opposed campaign finance reform on policy grounds and liberals have favored it. If you look at the vote on McCain-Feingold in the Senate, for example, 48 of the 59 "yes" votes were Democrats, with most of the 11 GOP Yes votes coming from moderates like Specter, Chafee, Collins and Snowe. In contrast, 38 of the 41 "no" votes were Republican, with the three Demoratics voting "no" being moderates like Ben Nelson.

  So for the most part, I think the votes in campaign finance cases pretty much just track the Justices' political views, without much more explanation required. An interesting exception is Justice Kennedy, who is a very strong opponent of campaign finance laws. I tend to think his opposition is not a result of his policy views or political commitments as much as a result of his consistently robust view of the First Amendment.