Update/related: Floyd Abrams, who represented the New York Times in the landmark Pentagon Papers case, with a letter to the editor of that paper correcting its grasp of the issues in the Citizens United decision:
The law at issue in Citizens United permitted The Times to endorse candidates while making it a felony for nonmedia corporations to do so. It made it a crime for a union to distribute [the Times's] endorsement of President Obama for re-election to its members. It should come as no surprise that the same First Amendment that was held to shield the press in landmark cases of the past now shields such speech as well.