Citizens United v Federal Election Commission was initially a narrow challenge to the McCain-Feingold legislation, the Bipartisan Campaign Reform Act (BRCA). However, the Supreme Court having heard the case in the last session on the narrow issues of the Video-on-Demand anti-Hillary movie, decided to rehear the case on a facial challenge, that is to test the constitutionality of the entire piece of legislation.
Together with former Kerry-Edwards internet guru Zack Exley and the Brennan Center at the NYU law school (among others), Calitics and the editorial board decided to join an amicus brief in favor of the constitutionality of the BCRA.
While this was by no means an easy decision, as there are some progressive groups on the other side in this case. In the end, we felt that the law not only adequately protected new media organizations, but also did a reasonable job of narrowly tailoring the regulations to regulate corporate campaign funds. The BCRA is far from perfect, very far in fact. However, given the sweeping first amendment protections offered by Buckley v Valeo, the BCRA is a decent attempt at getting some sort of campaign finance system in place. Further, striking down BCRA would make any future reform almost weaker by definition as Congress would have to avoid even more constitutional pitfalls.
The brief is fairly short for one of these things, so you can find it over the flip.