The government's ability to fight disinformation online has suffered a legal setback that experts say will have a chilling effect on communications between federal agencies and social media companies.

A Tuesday ruling by a federal district judge in Louisiana could have far-reaching consequences for the government's ability to work with Facebook and other social media giants to address false and misleading claims about COVID, vaccines, voting, and other issues that could undermine public health and erode confidence in election results.

District Court Judge Terry Doughty, who was appointed by President Donald Trump, issued a preliminary injunction on Tuesday that bars several federal departments and agencies from various interactions with social media companies.

On Wednesday, the Justice Department filed a notice that it will appeal the injunction with the Fifth Circuit Court of Appeals in New Orleans. The government also expects to ask the court to stay the district judge's decision, meaning it would not go into effect while the appeal is heard.

What is this lawsuit about?

The case, brought by the Republican attorneys general of Missouri and Louisiana, addresses what has become a highly contested subject: the demands by some conservatives for "free speech" on social media platforms, versus the desire to rein in misinformation and disinformation that could lead to real-world harm.

The AGs' argument ties into a larger Republican narrative that conservatives are being censored on social media for their views. Democrats have faulted the platforms for not doing enough to police misleading and false claims, hate speech, and incitement to violence.

"It's hard to think of a more sweeping ruling," says Evelyn Douek, an expert on the regulation of online speech and a professor at Stanford Law School.

"The injunction enjoins tens of thousands, maybe hundred [of] thousands of federal government employees from having almost any kind of communication with private platforms about content on their services," Douek tells NPR. She notes that while there are exceptions for certain types of criminal content, overall, the "clear message is to have this sort of chilling effect on communication between the government and platforms."

What does the judge's ruling say?

Doughty issued a temporary injunction blocking agencies including the departments of Justice, Health and Human Services, and State, the Centers for Disease Control and Prevention, the FBI and many individual government officials from doing things like notifying platforms about specific posts that may be against their own rules or asking for information about content moderation efforts.

The ruling provides exceptions for the government to inform social media companies about posts involving criminal activity, national security threats, and foreign interference in elections.

There are also a couple of pretty broad exceptions: Exercising "permissible public government speech promoting government policies or views on matters of public concern" is permitted, as is interacting with social media companies about posts that are not protected free speech.

The injunction bans interactions such as "meeting with social-media companies for the purpose of urging, encouraging, pressuring, or inducing in any manner the removal, deletion, suppression, or reduction of content containing protected free speech posted on social-media platforms".

It also blocks federal agencies from flagging specific posts that contain protected free speech, encouraging social media companies to change their guidelines regarding such posts, or asking the companies to "be on the lookout" for such postings.

Why does this matter?

This ruling severely curtails the federal government's ability to interact with social media companies about what appears on their platforms.

The injunction is written very broadly, potentially banning the Biden administration from even talking publicly about what moderation of social media content could look like.

Does the injunction specify which social media companies the government can't talk to about this content?

Yes. It lists Facebook/Meta, Twitter, YouTube/Google, WhatsApp, Instagram, WeChat, TikTok, Sina Weibo, QQ, Telegram, Snapchat, Kuaishou, Qzone, Pinterest, Reddit, LinkedIn, Quora, Discord, Twitch, Tumblr, Mastodon "and like companies."

What counts as "protected free speech"?

"That's clearly the $64,000 question," says Mark MacCarthy, a tech policy expert and senior fellow at the Brookings Institution. But he notes that no one is really disputing that the sort of content the lawsuit identifies the government communicating with tech companies about is protected speech.

"It was pretty clear on the part of everybody involved in this, that the speech involved was clearly protected by the First Amendment," he says. "It was statements about whether the election was fraudulent or accurate. It was statements about whether vaccines worked or not. And while those things maybe have scientific answers, the unscientific answers are clearly protected speech."

The Biden administration says it isn't telling social media companies what to take down or how to set policies, but that it has an interest in promoting accurate information about urgent issues like public health and elections, and curbing the spread of illegal material including terrorism and child sex abuse.

What else is in the injunction?

The ruling also prevents federal officials from working with third parties including the Election Integrity Partnership, the Virality Project, and the Stanford Internet Observatory — three academic research groups that track the spread of online information. Republicans have accused the Biden administration of attempting to outsource its alleged efforts to stifle speech to outside organizations and academics.

How big of a change will this be? Do we know how much the government has been working with social media companies to remove or suppress this content?

Douek says not enough is known about what sort of contact tech companies regularly have with government agencies and officials. "If there's any sort of saving grace or positive of this judgment, it's to sort of shed some light on the kinds of relationships that the platforms have," she says.

Social media companies have a wide range of relationships with governments, she says, from informal conversations to formalized reporting mechanisms to regular private meetings. These interactions accelerated after the 2016 election, reflecting criticism that tech platforms had not done enough to combat Russian efforts to interfere in the presidential race, and again during the pandemic, when officials worried that false and misleading social media posts could erode confidence in vaccines and advice from public health experts.

Douek says it's legitimate to ask about the relationships between platforms and the government and how to balance the government's interest in promoting accurate information against the threat of governmental overreach.

But she says Doughty's ruling is "painting with a very broad brush and saying any and all contact is really problematic. And I think that that goes too far and will have dramatic ramifications for the way that these platforms operate."

MacCarthy says the judge's tone was "a little bit over the top" and "apocalyptic," but the free speech issues involved in the case are real.

"I know it's a matter of the paranoia of the conservative groups that they're being victimized by shadowy agents and the government," he says. "But these are not one-sided partisan issues here. These are issues that everyone should be concerned about."

What does the Biden administration say about this?

The Justice Department is reviewing the injunction and will evaluate its options in the case, a White House official told NPR.

"This administration has promoted responsible actions to protect public health, safety, and security when confronted by challenges like a deadly pandemic and foreign attacks on our elections," the official said in a statement. "Our consistent view remains that social media platforms have a critical responsibility to take account of the effects their platforms are having on the American people, but make independent choices about the information they present."

Have social media companies responded?

NPR reached out for comment from Meta (the parent company of Facebook and Instagram), Google and Twitter. None had any comment on the ruling.

What happens next?

The Biden administration is appealing the ruling, and the case may ultimately make it to the Supreme Court. The White House has regularly criticized tech companies for not doing enough to combat false and misleading claims about public health and elections on social media. The current conservative-leaning Supreme Court has ruled in favor of First Amendment rights over other considerations recently, including siding with a web designer who did not want to have to work with same-sex couples.

Even before this ruling, social media companies had already been backing off policies about COVID-19 and election integrity as they have come under pressure from Republican politicians and conservative activists — suggesting how politicized this topic has become and will continue to be.

NPR's Emily Olson contributed reporting.