Citizens United is a major case with a lot of importance to free speech. Sadly, most of the reporting on the case was either intentionally or accidentally misleading. So, here's an informal case brief so that you can understand the case.
Of course, this decision is massive, and "informal" means no footnotes, citations, or authority's list. Justice Kennedy wrote the opinion, and the core of the argument was 5-4.
Prior to the Citizens United case, there was a case that held that speech by a corporation could be banned outside of special political funds with strict limits on funding. Austin was directly challenged by the petitioners (Citizens United, the people who appealed). The current decision noted that Austin contradicted First Amendment principles and, in part on that basis, overturned it. The Court held that the government may require disclaimer and disclosure, but may not ban or limit speech altogether.
The Court first reviewed the facts of the case. Citizens United is a non-profit corporation that produced the film, "Hillary: The Movie". The film was an extended the attack on then-Senator Clinton, who was running for President. Citizens United wanted to release the video on-demand for free. Citizens United itself was prepared to pay the costs of distribution as well as pay to air some ads promoting the video. Each ad contained negative statement about Hillary Clinton and promoted the film.
Federal law prohibited corporations from donating to candidates or spending money to support or attack them. Then BCRA came along and prohibited anyone from even referring to a Federal candidate on broadcast TV, radio or cable within a month of a primary or two months of a general election. In relation to the Presidential election, speech that reaches less than fifty-thousand people is exempted.
Citizens United challenged the law, as they planned to have the film available during the prohibited time frame. Citizens United challenged both the ban, and the disclosure requirements. The District Court held that the ban on speech was Constitutional because it expressly banned political speech by corporations. It upheld the disclosure requirements as well.
The Court first attempted to find a ground to avoid overturning Austin by seeking narrower grounds to decide the case. The Court held that the law clearly covered the movie, as it was political and could reach more than fifty-thousand people. The Court also held that it would not create an unworkable mess to save the law. The Court also held that it was "express advocacy" - material calling for the election or defeat of a candidate for office, specifically Hillary Clinton's Presidential campaign. The Court also rejected the argument that the movie was just a typical documentary by quoting the first and last lines of the movie.
The Court continued on this path by tossing an argument that video on-demand should be exempt because it cannot "distort" the political marketplace. The Court refused to create preferred mediums, rulings that would themselves violate the First Amendment. The Court continued in this vein, rejecting all the remaining limited-scope arguments. The Court was forced to conclude that is was not possible to decide the case without either chilling speech or deciding the First Amendment issue.
The Court then moved to the Constitutional claim. It begin by citing the First Amendment (obviously) and reviewing a number of unlawful restrictions, from before the speech would be given to following up after the speech. It then characterized the law as "an outright ban, backed by criminal sanctions" and reviewed examples of illegal conduct under the law, from critical ads from the Sierra Club or the NRA, to an ACLU website supporting a candidate. It called these "classic examples of censorship."
The Court eliminated the idea that a Political Action Committee was a sufficient alternative for corporations to speak. The most important issue was that PACs are separate organizations; having an agent to speak on someone's behalf is not the same as being able to speak on their own. On top of that, PACs carry a lot of burdens and filings with them, including donor lists, a separate treasurer, and even extensive monthly reports. And on top of that, PACs take time to set up and develop. For these reasons, the Court rejected PACs as the only venue for speech.
The Court reviewed the precedent that a restriction on spending money to speak is a restriction on the speech itself, and reviewed the importance and purpose of speech itself. The core elements of free speech include a protection of the speech itself, so the viewpoints or ideas are not stifled, and likewise a protection of speakers, so that individual speakers are not given special privileges or limited freedom. The points are connected - speaker restrictions are often intended as speech restrictions.
The Court then cited a full page of nothing but case citations, precedent establishing that corporations have First Amendment protections, including for political speech. The Court established a long history of long history of dismissing the idea of speech protections only for "Natural Persons".
Reviewing the history of the speech laws, the Court observed that the first ban on corporate speech was not passed until 1947 over the veto of President Truman. While the the law took some time to reach the Court, the Court repeatedly narrowed the scope of the law to not cover the conduct at issue or avoided the Constitutional question entirely.
The most important case in this vein is Buckley v. Valeo, which established that the government could prohibit corporate donations and impose donation limits to prohibit quid pro quo corruption - money for benefits or the appearance thereof. Buckley did not address the issue of unco-ordinated expenditures of corporations acting on their own, but eliminated the existing ban on expenditures entirely.
After Buckley, a state prohibition on corporate spending was explicitly struck down, on the grounds that the government cannot disfavor corporate speakers, period.
Then Austin came in and the Court created a new justification for speech bans - anti-distortion. Austin created a compelling interest in banning speech from corporation because they have too much money and therefore could speak too much.
The government argued in Citizens United that the Court expand the anti-corruption rationale and create a shareholder-protection rationale as well. It mentions in passing Austin's anti-distortion rationale.
The Court hit Austin's creation first. The First Amendment protects citizens or association of citizens from jail for speaking, or it serves no purpose at all. Austin's permission to ban all corporate speech, including the publishing of books cannot be reconciled with the First Amendment.
The Court than attacked the distortion rationale directly. First Buckley rejected the rationale prior to Austin, and this Court held that the First Amendment doesn't go away because the speaker is wealthy or influential. The Court has repeatedly rejected any device that allows the government to "balance" speakers, either by supporting favored ones or attacking disfavored ones. It also dismissed the Austin argument that the advantages of the corporate form allowed the government to demand basic rights in exchange/
Neither does the public support of speech determine its protected status. In fact, the speech most in need of protection is the speech that is least popular.
And the distortion rationale would allow Congress to ban the political speech of media corporations. Austin's rule justifies government regulation of the press, a concept anathema to the Constitution. The Court has consistently rejected the idea of the press as a separate and special class that the First Amendment press protection applies too. The First Amendment protects political speech for everyone, and does not allow the government to select favored speakers or designate anyone as press entitled to special protections.
The Court also mocked Austin's rationale that corporations are repositories of vast wealth by pointing out that some 96% of corporations have less than 100 employees and 75% have less than one million dollars of gross receipts annually. The rationale isn't even aimed in the direction of wealth.
Describing the censorship as "vast", the Court attacked the law as silencing "the voices that best represent the most significant segments of the economy" and cheating the public of "information, knowledge and opinion vital to its function."
The Court also pointed out a ridiculous effect of the Austin rules - that major corporations may privately lobby government officials without limit, yet smaller corporations who cannot hire lobbyists may not lobby the public directly. What's more, public officials may privately coerce corporations into serving government ends, and no corporation may publicly object to such a thing.
After gutting the Austin rationale, the Court turned to the corruption interest. Except Buckley, which established that interest, rejected it for expenditures. This Court refused to expand the anti-corruption rationale as, absent specific co-ordination, there was no chance for quid pro quo exchange. The Court pointed to the many states without such a prohibition to drive the point home. The Court also tossed the argument that the enhanced legislative access is what counts as quid pro quo. Such things are simply unavoidable parts of politics.
The government also argued that the Court to protect shareholders from supporting speech they disagree with. This would again result in government authority to prohibit media corporations from making opinion statements, on the basis of one shareholder disagreeing with the corporate opinion. The Court rejected the argument on both First Amendment grounds and on the grounds that the corporate structure already addresses the issue. The shareholder argument not only captures single-shareholder corporations with no one to dissent in an overreach, but only "protects" shareholders of larger corporations during the blackout period in an underreach.
The Court mentioned that neither the law nor the decision addresses the issue of foreign corporations.
The Court addressed the justifications for overturning Austin. That case was that it; directly offended the First Amendment", overturned aspects of two other cases, was historically flawed, was widely evaded by the public, and unnecessarily restricts new forms of speech created or improved by technology.
No one, save state legislatures, relies on Austin, which also diminishes the incentive to uphold the case.
The Court did uphold the disclosure requirements with the caveat that any group faced with a risk of retaliation for speaking would have an as-applied challenge to disclosure. Disclosure is a small, minor burden that serves a greater interest in accountability than it harms the speech.