The arguments before a three-judge panel of the 11th U.S. Circuit Court of Appeals followed a ruling last year by U.S. District Judge Robert Hinkle, who sided with online-industry groups that argued the law — one of DeSantis' top 2021 legislative priorities — violated the First Amendment.

NetChoice and the Computer & Communications Industry Association, groups that represent tech titans such as Twitter, Facebook and Google, filed the lawsuit. The law, in part, sought to prevent large social-media platforms from banning political candidates from their sites and to require companies to publish — and apply consistently — standards about issues such as banning users or blocking content.

Hinkle issued a preliminary injunction a day before the law was slated to go into effect on July 1, 2021.

The industry groups argued the measure violated the First Amendment rights of companies and would harm their ability to moderate content on the platforms.

Lawyers for the state have maintained that the social-media groups are quashing users' speech rights.

Brian Barnes, a private lawyer who represents the DeSantis administration, defended the restrictions during Thursday's arguments, which were held in Montgomery, Ala.

Barnes told the three-judge panel that large social-media platforms such as Twitter — which has roughly 300 million monthly users — should be regulated in the same way as "common carriers," which can include such things as transportation and telecommunications businesses.

Under intense questioning from Judge Kevin Newsom, Barnes said common-carrier regulations should apply because users are stuck with large social-media platforms, once they sign onto the services.

"When a social-media platform becomes large enough, there's this dynamic where it becomes very difficult for people who've joined the platform to switch to a different platform," Barnes said. "And what the Legislature's trying to get at is this sort of market failure where the network effect prevents people from switching in response to a problematic content-moderation policy, in response to the unfair application of a stated content-moderation policy."

DeSantis made the issue a priority after former President Donald Trump was blocked from Facebook and Twitter after Trump supporters stormed the U.S. Capitol on Jan. 6. The governor and Republican lawmakers described the law as protecting free speech.

As an example of potential penalties in the law (SB 7072), companies that violate the prohibition on banning political candidates from platforms could face fines of $250,000 a day for statewide candidates and $25,000 a day for other candidates.

The industry groups' lawsuit and request for a preliminary injunction argued, in part, the measure was politically motivated. The law was designed to address large online platforms, as it applied to companies that have annual gross revenues of more than $100 million or have at least 100 million monthly individual "participants" globally.

"At its core, (the bill) upends the rights of a targeted group of online services to decide what material to display and how that material should be presented," a legal memorandum filed by plaintiffs said. "In other words, the act takes away these private companies' ability to make editorial judgments — a fundamental component of the 'freedom of speech' protected by the First Amendment. Indeed, the act is designed to single out certain online services for special limits on their speech because of the state authorities' open hostility to their perceived political views and 'ideology.' The law is blatantly unconstitutional."

Hinkle's ruling last year called the law "riddled with imprecision and ambiguity."

"The legislation now at issue was an effort to rein in social-media providers deemed too large and too liberal. Balancing the exchange of ideas among private speakers is not a legitimate government interest," Hinkle wrote in a 31-page order.

Paul Clement, a former U.S solicitor general who represents the tech-industry groups, told the three-judge panel — comprised of Newsom and Judges Gerald Tjoflat and Ed Carnes — that the law's focus on large social-media companies illustrates its flaws.

As they passed the law last year, Republican legislators inserted a theme-park exemption that was designed to shield Walt Disney Co. from the social-media restrictions. But they reversed course during a special session last week and removed the exemption after Disney clashed with DeSantis and GOP lawmakers about new state prohibitions on teaching about gender identity and sexual orientation in public schools.

During Thursday's arguments, Newsom asked about the removal of the theme-park exemption.

"The carveout for a subset of big social media platforms … just really is terrible," Clement argued. "In a sense they (the Legislature) just kind of doubled down … It's almost like a test case or a real world demonstration of why speaker-based distinctions are problematic."

Clement likened the tech statute to a law that would apply only to newspapers with a circulation of 1 million or more, except for in-state publications.

"And then one of the in-state newspapers just rips into the Legislature and they say, 'Forget that, we're gonna get rid of that little carveout of the in-state ones.' I think it would show that the whole thing was kind of rotten at the core," he said.