As Congress and President Joe Biden edge closer to barring the immensely popular video sharing app TikTok Inc from devices in the U.S., free speech advocates are preparing for a fight that would pit the First Amendment against lawmakers’ concerns about national security.

Sixteen public interest groups, including the ACLU, the Authors Guild and the Knight First Amendment Institute issued a letter to Congress last week, warning that a wholesale ban on TikTok was an “ill-advised, blanket approach that would impair free speech and set a troubling precedent.” The Electronic Frontier Foundation published a similar policy statement earlier in March, arguing that government has not offered enough specific evidence about TikTok’s national security risk to justify an outright ban.

Defenders of any TikTok ban, led by the U.S. Justice Department, will surely deny that it intrudes on free speech rights. In fact, if the ban relies on restricting app sales and internet hosting services for TikTok's Chinese parent company, ByteDance Ltd, the Justice Department will likely argue that it doesn't even implicate the First Amendment because it's aimed at commercial transactions, not speech.

The looming First Amendment fight over TikTok will obviously depend on the specifics of any ban. But some basic principles underlie the argument.

To start, TikTok – as a U.S.-incorporated subsidiary of ByteDance – and its U.S. users are both entitled to free speech protection under the First Amendment. So both, according to Knight First Amendment executive director Jameel Jaffer, would have standing to raise a First Amendment challenge to a ban.

Even TikTok users who merely watch videos without posting their own content, Jaffer said, have a First Amendment right to receive information. That right, he said, extends to propaganda from a foreign government under the U.S. Supreme Court’s 1965 decision in Lamont v. Postmaster General, which struck down a federal statute that required people who had been sent “communist political propaganda” to fill out a government form before they could receive the mail.

But the Supreme Court has also held that the First Amendment does not preclude the government from shutting down a business that distributes information if that business is used for illicit activities. In 1986’s Arcara v. Cloud Books, Inc., the justices sided with New York officials who shuttered an adult bookstore suspected of being a prostitution hub, rejecting the bookseller’s argument that the closure violated his free speech rights.

“The government is looking at conduct, not speech,” said Joel Thayer of the Digital Progress Institute, who has called for ByteDance to divest ownership of TikTok. “I’d push back on the idea of First Amendment implications.

If the Biden administration attempts to foreclose U.S. users from accessing TikTok at all, it’s a good bet that the Justice Department will rely on Arcara precedent to defend the ban.

I can say that with great confidence because the case figures prominently in Justice Department briefing in two previous cases challenging a ban on TikTok.

That's right, previous cases. In 2020, when former President Donald Trump issued executive orders that would effectively have barred TikTok from operating in the U.S., TikTok and three TikTok users filed separate lawsuits to block the orders from taking effect. TikTok’s lawyers at Covington & Burling sued in federal court in Washington, D.C. TikTok users, represented by Davis Wright Tremaine, sued in Philadelphia federal court. (Neither Covington nor Davis Wright responded to my queries about the prospect of new litigation.)

The federal judges overseeing both cases avoided a reckoning on First Amendment issues. Instead, U.S. District Judges Wendy Beetlestone of Philadelphia (in the TikTok users’ case) and Carl Nichols of Washington (in TikTok's own case) granted preliminary injunctions because Trump's orders ran afoul of a 1988 statute known as the Berman Amendment, which restricts the president’s authority to use emergency powers to ban the importation of information from foreign countries. The Justice Department appealed those rulings but dropped the appeals after the Biden administration rescinded Trump’s TikTok orders.

Congress is now considering legislation that, in effect, would loosen the Berman Amendment’s constraints, removing the statute as an obstacle for presidential action on TikTok. That, in turn, which would make the First Amendment the primary line of attack on a TikTok ban.

The Justice Department, as I mentioned, argued in the 2020 TikTok users’ case that any First Amendment analysis should focus on actual prohibitions – including a ban on internet hosting services for ByteDance – rather than the downstream impact on TikTok users.

“The restrictions here do not trigger First Amendment scrutiny because they regulate only economic transactions based on national-security concerns,” DOJ asserted. “Any effects on speech are incidental.” (Justice Department lawyers also argued that TikTok users would have access to plenty of other platforms to share and consume videos.)

But David Greene of Electronic Frontier Foundation told me that the government can’t entirely evade challengers’ First Amendment arguments by claiming that a TikTok ban only regulates commercial transactions, not speech. At best, he said, such an argument might persuade a court to examine the First Amendment implications of the TikTok ban using an intermediate level of scrutiny.

That inquiry, which is the usual standard for broad-based, “content-neutral” speech restrictions, would require the government to show that it narrowly tailored speech limitations to serve an important government interest. No one would argue that national security is not an important interest, of course, but TikTok, TikTok users and their supporters will likely assert that a wholesale ban is too blunt an instrument.

That strategy, after all, worked for users of the China-based messaging and social media platform WeChat, which the Trump administration effectively banned in 2020. U.S. Magistrate Judge Lauren Beeler granted a preliminary injunction against the restrictions, ruling that its users were likely to prevail on their claims that the ban was an overly broad response to the threat it was intended to address.

Beeler’s ruling was not tested through an appeal because the Biden administration dropped the WeChat ban. But you can bet it’s getting a thorough reading from lawyers waiting for action on TikTok.

(Reporting By Alison Frankel, editing by Leigh Jones)