When Democratic politicians complain about the Citizens United decision, what they are complaining about is their loss of the power to censor political thought and media in America. This is the movie that the FEC prohibited from being shown in America during the 2007–2008 presidential campaign.
Citizens United is a non-profit corporation, which made Hillary the Movie, a documentary critical of Hillary Clinton, then a candidate for president. The Supreme Court ruling in Citizens United v. FEC overturned the portion of the McCain-Feingold campaign finance law that allowed the government, in this particular historical case, to stop a movie from being shown in America.
Imagine what Democrats would say (rightly) had the Federal government tried to prohibit Michael Moore’s Fahrenheit 911.
As a proponent of free speech and the press, you may even be, ahem, obligated to watch this artifact of our history — which is timely once again now that Mrs. Clinton is in the news, considering another run for the presidency.
The Citizens United website has links to the full decision and more.