While libraries across the country encouraged readers to crack open a previously censored book for Banned Books Week this month hopefully you made time for a movie.

Banned Books Week is a celebration of the freedom to read, but also a celebration of the freedom to seek out and share ideas, no matter how controversial they may be. In today’s world, where people acquire their information from increasingly diverse sources, it’s important to remember that the principles supporting the free flow of ideas are not contingent upon the medium used to express them. If you wouldn’t ban a book, you shouldn’t ban other means of communicating the same ideas.

Keeping this in mind keeps free speech free even as technological advances change the way we consume and share information. In fact, it was the specter of book-banning that saved free speech in film in 2010, when the Supreme Court was asked whether the Federal Election Commission (FEC) could prohibit the distribution of a movie near an election if it was funded by a corporation and mentioned a political candidate.

To an onlooker, the question may seem bizarre. Movie studios and theatre houses take the corporate form. Films with political messages, from “All the President’s Men” to the works of Michael Moore, are commonplace. So, what’s the problem?

The problem was the FEC and our federal campaign finance laws, which claimed that “Hillary: The Movie,” a film by the nonprofit group Citizens United, could be effectively banned near the 2008 election because it criticized Hillary Clinton, who was a candidate for President at the time (and at present, coincidentally). According to federal regulations, Citizens United was prohibited from distributing its film over pay-per-view and was unable to advertise it on television.

The Supreme Court saw an obvious threat to free speech: if Citizens United can be prohibited from showing a movie critical of a political candidate, what about other corporations? And, if corporations can be prohibited from producing or distributing movies that criticize candidates, what about publishing a book that says the same thing?

During oral argument, Justice Samuel Alito asked the government’s lawyer, “What’s your answer to [the] point that there isn’t any constitutional difference between the distribution of this movie on video demand and providing access on the Internet, providing DVDs… or maybe in a public library, providing the same thing in a book? Would the Constitution permit the restriction of all of those as well?”

The government’s answer? “I think the – the Constitution would have permitted Congress to apply the [restrictions] to the extent that they were otherwise constitutional under [existing precedent].  Those could have been applied to additional media as well.” He continued to speak, but Justice Alito interjected.

“That’s pretty incredible,” he said. Indeed it was. The exchange continued as Alito pressed the government to answer whether a 500-page book with just one line urging people to vote for a candidate could be banned. The government argued that if it was published with corporate funds, then yes, it could be banned near an election.

Suddenly, the stakes of the case rose sky-high. Barnes & Noble is a corporation. Simon & Schuster is a corporation. The New York Times is a corporation. Could they all be prevented from publishing or distributing content about political candidates?

Recognizing the danger of such broad government power, the Supreme Court ruled in favor of Citizens United. Now, media corporations and wealthy individuals no longer hold a monopoly on funding political films, advertising, and other modes of communication. Thanks to Citizens United and subsequent rulings by lower courts, anyone can easily form a group that accepts contributions from like-minded people to make their political voice heard.

Not everyone is happy with Citizens United, just like not everyone is happy that people can read books they personally consider offensive or obscene. Fortunately, their objections continue to lose in court. The First Amendment guarantees everyone the right to express themselves in the way they see fit, and to seek out the views of others, no matter what offended onlookers or government bureaucrats think about it.

Luke Wachob is the McWethy Fellow at the Center for Competitive Politics in Alexandria, VA