Recent federal court activity has dramatically changed the regulatory environment of campaign finance in the United States. Since 2010, the judiciary has decided that corporations and labor unions may freely spend in American elections, and that so-called "Super PACs" can accept unlimited contributions from private citizens for the purpose of buying election advertising.

Despite the potential for such unregulated contributions to dramatically alter the conduct of campaigns, little is known about where Super PACs get their money, where they spend it, or how their message compares with...

Recent federal court activity has dramatically changed the regulatory environment of campaign finance in the United States. Since 2010, the judiciary has decided that corporations and labor unions may freely spend in American elections, and that so-called "Super PACs" can accept unlimited contributions from private citizens for the purpose of buying election advertising.

Despite the potential for such unregulated contributions to dramatically alter the conduct of campaigns, little is known about where Super PACs get their money, where they spend it, or how their message compares with...