The Supreme Court hears a pair of cases Monday that could help define the future of the Internet.

Legal experts say they're the most important First Amendment cases in a generation. The question is whether states like Florida and Texas can force big social media platforms to carry content the platforms find hateful or objectionable.

"There is nothing more Orwellian than the government trying to dictate what viewpoints are distributed in the name of free expression," said Matt Schruers, president of the Computer & Communications Industry Association, a trade group for the social media companies that's involved in the litigation. "And that's what's at issue in this case."

The dispute intensified after the violent siege on the U.S. Capitol in 2021, when social media sites booted former President Donald Trump from their platforms, fearing his posts could provoke more unrest.

Republicans in Florida and Texas took action, signing sweeping laws that prevent the largest platforms from banning users based on their political viewpoints and require them to provide an individual explanation to users about why their posts have been edited or removed.

"Freedom of speech is under attack in Texas," declared Texas Republican Gov. Greg Abbott at the bill signing. "There is a dangerous movement by some social media companies to silence conservative ideas and values. This is wrong and we will not allow it in Texas."

A separate law in Florida prevents the social media platforms from rapidly changing their terms of service, and threatens huge financial penalties.

The social media companies sued, citing Supreme Court precedent that says state and federal governments cannot force people or businesses to speak. Schruers, who leads the industry trade group, said the state laws interfere with how the companies operate, from their basic policies to editing, deleting or adjusting posts, across all content.

"It is necessary to have guidelines and terms of use to make sure that a community isn't polluted," Schruers said. "And that's everything from posting dog pictures in the cat forum to barbeque in the vegan forum to far more serious things like trying to groom children in a children's site."

The states' arguments

In court papers, lawyers for Texas and Florida said the social media platforms are discriminating against conservative views.

John Whitehead runs the Rutherford Institute, a conservative-leaning nonprofit group. Whitehead, who filed a friend-of-the-court brief in the cases, said the big social media sites have become the center of people's lives and they should not be engaging in any censorship.

"It's out there to make people think," Whitehead said. "In other words, you can disagree. If someone puts something foolish on, let's say, Facebook, people should respond immediately and start a debate. Debating is the key, not eliminating."

Other allies of Texas and Florida argue the sites are merely hosting content, not making editorial judgments that deserve lots of First Amendment protection.

Carl Szabo is general counsel of Netchoice, another big trade group for social media platforms that's involved in these lawsuits.

"These cases are going to define the future of the Internet," Szabo said.

At stake, he said, is who controls what people hear, say and read online.

"Everyone, left right or center, should oppose government control of speech," Szabo said. "Because as it may be your person in the White House today, we know that that will not be forever. And that's why the First Amendment is so important and so paramount."

What the justices will have to decide

The justices will have to decide between radically different conceptions of what social media is. Are these platforms more like old-time phone companies: basically, open to everyone without filtering?

Or, are they more like like bookstores and newspapers, places that edit and curate information, that get the highest level of First Amendment protection?

The social media giants are relying in part on a 1974 Supreme Court case, Miami Herald v Tornillo. Florida tried to force the newspaper to carry op-eds it didn't want to publish. The high court sided with the Herald back then.

Today, the social media sites said, Florida is trying to make the big social media platforms print every single letter to the editor. Users don't want that and neither do advertisers, they said.

Support for the tech companies

The two trade associations — Netchoice and CCIA — are backed by groups across the political spectrum, from the U.S. Chamber of Commerce and Americans For Prosperity, which is linked to Charles Koch, to the American Civil Liberties Union.

A bipartisan group of national security experts weighed in, too. Rupa Bhattacharyya is a former Justice Department lawyer and special master for the September 11th Victim Compensation Fund. She now works at the Institute for Constitutional Advocacy and Protection at Georgetown University Law Center.

"Social media content moderation plays a really important role in keeping some of the worst of the hate and the violence off of the Internet," Bhattacharyya said.

Home-grown extremists like the Proud Boys and foreign groups like the Islamic State have deployed social media to attract converts and broadcast violence. The Christchurch mosque shooter in New Zealand live-streamed his activities, to try to inspire others, she added.

Bhattacharyya said social media platforms should face common-sense regulations, including consumer protection and anti-fraud laws. And the current content moderation policies of some of the big sites have real flaws.

But Bhattacharyya said, "They are better than nothing."

And she said nothing — no content moderation at all — is what will happen if the Supreme Court upholds the sweeping laws in Texas and Florida.

Volunteer moderators of a Reddit site devoted to law and the Supreme Court filed their own brief in the cases to deliver a very particular message.

Their court papers cited hateful speech and threats against the justices. Moderators said they delete those things now. But under the state laws, they might face lawsuits for yanking "trolls" who flood their chats with vulgar and racist posts.

The state laws are not about protecting speech, the moderators wrote. Instead, they're commandeering someone else's microphone to spread a message.

NPR Legal Intern Elissa Harwood contributed to this report