UPDATE: Facebook's general counsel posted a response to Sen. Thune's letter on May 23, 2016.

Allegations that Facebook’s “trending” news stories are not actually those that are most popular among users drew the attention of Sen. John Thune (R-SD), who sent a letter of inquiry to Facebook suggesting that the company may be “misleading” the public, and demanding to know details about how the company decides what content to display in the trending news feed. Sen. Thune appears particularly disturbed by charges that the company routinely excludes news stories of interest to conservative readers.

Congressional inquiries usually come with the tacit understanding that Congress investigates when it thinks it could also legislate. Yet any legislative action in response to the revelations would run afoul of the First Amendment. It is possible that Sen. Thune, as chairman of the Senate Commerce Committee, sees Facebook as engaging is “unfair or deceptive” trade practices, but that still does not create a legal basis for regulating what amounts to Facebook’s editorial decision-making.

First Amendment Protects Facebook’s Editorial Decisions

In Miami Herald Publishing Co. v. Tornillo (1974), the Supreme Court held that under the First Amendment, the government may not tell a private publisher what to print or not to print, nor may the government punish a publisher for making editorial decisions. The Court stated:

The choice of material to go into a newspaper, and the decisions made as to limitations on the size and content of the paper, and treatment of public issues and public officials—whether fair or unfair—constitute the exercise of editorial control and judgment.

Although that case involved a newspaper, the constitutional rule is just as applicable to the Internet, where a wide range of websites—from newspapers’ digital homes to social media platforms native to the online space—have the right to be free from government interference with their publishing practices.

Even if Congress never takes any action, Sen. Thune’s letter alone—questioning Facebook’s editorial decisions—is an improper intrusion into editorial freedom. Moreover, such an official government inquiry into constitutionally protected activity can create a “chilling effect” that dissuades individuals, even companies, from acting in wholly legal ways.

Sen. Thune’s letter is a close cousin to the tactic deployed by the sheriff of Cook County, Illinois, who wrote letters on official letterhead urging credit card companies to stop providing payment processing services to classifieds websites like Backpage.com, while suggesting that the companies might be legally culpable if they refused to heed the sheriff’s request. Backpage challenged the sheriff’s actions and the Seventh Circuit Court of Appeals held that the sheriff violated the website’s First Amendment rights.

As a Republican, Sen. Thune seems offended that Facebook might be purposefully excluding conservative news stories. But conservatives were outraged when the FCC proposed conducting a newsroom survey in 2014. Republican lawmakers and conservative commentators complained that the Obama administration was maneuvering to control media content in violation of the First Amendment. And Sen. Thune himself, in 2007, criticized those in Washington, DC, who, he said, were “reviving an old idea that the government can, and should, regulate the reporting of news, information and ideas.”

Facebook Should Be Fair and Transparent About Its Content Policies

There is a distinction that we want to emphasize: Facebook as a curator of news stories—exercising editorial judgment just like any other media outlet—and Facebook as a social media platform and host of user-generated content.

As a legal matter, in both roles, Facebook is protected by the First Amendment and thus has a right to publish content online free from government interference. As a policy matter, however, it would behoove the company to be more transparent about its content policies.

While it is understandable that Facebook users might want more transparency about what goes into producing the “trending” news feed (including whether the company is exercising political bias), we are more concerned about how Facebook acts in its more prominent role as a host of user-generated content.

As a social media platform, Facebook solicits and displays often highly personal text and images that individuals post to express themselves and connect with their loved ones and communities. People around the world have come to significantly rely on Facebook, even in life-and-death situations.

Yet the company reorders, emphasizes and minimizes posts to everyone’s news feed. And it enforces its terms of service in a selective manner: deleting some posts, censoring some images, and throwing some users off its service, while letting other apparent offenders go unpunished. We have criticized Facebook for unclear content policies and arbitrary enforcement of its terms of service.

At onlinecensorship.org, EFF is tracking such behavior by private social media companies. Whether a company justifies its actions by referencing its terms of service or some other reason, we want to better understand patterns in social media censorship. We encourage individuals who have had their own content removed or their account suspended to report their experiences there.

Facebook has a right to make its own decisions about what it does or does not say online. But it when it comes to providing a service that enables others to speak as well, Facebook should be fair and transparent about how it handles other people’s content—and the company should always expect to have its decisions explored and debated by its users and the wider public.