House lawmakers are moving with dizzying speed with a plan that could ban TikTok from the United States. In the span of two days this week, a key House committee introduced and approved a bill targeting TikTok. The full House is set to vote on it as early as next week, and the White House says President Joe Biden is prepared to sign it.But could a TikTok ban really happen? And what makes this proposal different from the other times policymakers have tried to clamp down on the video-sharing app used by 170 million Americans?Here's everything you need to know about the hot-button legislation:What would the bill do?If enacted, the bill would give TikTok roughly five months to separate from its China-linked parent company, ByteDance, or else app stores in the United States would be prohibited from hosting the app on their platforms.It doesn't stop there. The bill lays out similar restrictions for any app allegedly controlled by foreign adversaries, such as China, Iran, Russia or North Korea. And it sets up a process for Biden – or any future president – to identify apps that should be banned under the legislation.App stores that violate the legislation could be fined based on the number of users of a banned app. The bill establishes fines of $5,000 per user of a banned app. So in the case of TikTok, Apple and Google could potentially be on the hook for up to $850 billion in fines each.The House Energy and Commerce Committee voted unanimously to advance the bill on Thursday.What is TikTok saying?TikTok is calling the legislation an attack on the First Amendment rights of its users. It launched a call-to-action campaign within its app, urging users to call their representatives in Washington to oppose the bill. Multiple congressional offices say they've been flooded with calls."The government is attempting to strip 170 million Americans of their Constitutional right to free expression," TikTok said in a statement. "This will damage millions of businesses, deny artists an audience, and destroy the livelihoods of countless creators across the country."Why are lawmakers cracking down on TikTok?They allege TikTok poses a national security threat because the Chinese government could use its intelligence laws against ByteDance, forcing it to hand over the data of U.S. TikTok users. Policymakers worry that that information could then be used to identify intelligence targets or enable disinformation or propaganda campaigns.So far, the U.S. government has not publicly presented any evidence that China has accessed TikTok user data, and cybersecurity experts say it remains a hypothetical – albeit seriously troubling – scenario.Didn't President Donald Trump try to do this once? What's he saying now?Yes. While in office, Trump used a series of executive orders to try to force ByteDance to sell TikTok, and to bar app stores from hosting the platform. Those efforts stalled amid legal challenges, but Trump played a key role in making TikTok an issue in the first place, linking it to a broader anti-China agenda that included a trade war and incendiary rhetoric that's raised fears of anti-Asian hate.Curiously, however, Trump this week came out against a TikTok ban, saying in a post on Truth Social that it would only empower Facebook and Meta CEO Mark Zuckerberg, whom he described as "a true Enemy of the People!"It’s not clear why Trump abruptly reversed his stance on TikTok. Trump is the presumptive Republican nominee for president, who will likely take on Biden in this November’s election.So what makes this time different?First, we're talking about congressional legislation, not executive action. That's an important difference. During the Trump administration, some debated whether the president has the authority to ban a foreign-owned social media app. This bill would instead create clear, all-new authorities for the president to do exactly that.Second, Trump's efforts to ban TikTok ran into serious First Amendment objections at the time. The lawmakers behind this week's bill say they have worked hard to iron out those concerns.Video above: About 3 in 5 Americans view TikTok as a threat to national securityWisconsin Republican Rep. Mike Gallagher, one of the bill's lead cosponsors, says the bill does not ban TikTok; it simply offers TikTok the choice to be divested, with the consequence of a ban if it doesn't comply. Gallagher says he and others have worked on the bill for the past six months, consulting with officials from the White House and across Washington to ensure it can withstand a legal challenge.And, notably, White House Press Secretary Karine Jean-Pierre has publicly announced administration support for the bill."We welcome it," she told reporters this week. "Obviously, we've been working with on it. And we would want to see this bill get done so it can get to the president's desk."Biden expressed support as well.“If they pass it, I’ll sign it,” Biden told reporters at Joint Base Andrews on Friday.Can it actually pass?The bill is advancing remarkably quickly in the House. With how quickly House leaders are promising a floor vote, it suggests they are confident it has enough votes to clear the chamber.The question is whether the bill has a future in the Senate. If it's taken up there, Gallagher said, it would likely fall to the Senate Commerce Committee. There is currently no companion bill to the House bill in the Senate, however. And Washington Sen. Maria Cantwell, who chairs the Commerce Committee, has provided a largely non-committal statement on the bill that acknowledges the concerns of its opponents."I will be talking to my Senate and House colleagues to try to find a path forward that is constitutional and protects civil liberties," Cantwell said in a statement to CNN.Does the bill violate the First Amendment?Civil society groups say that even if the bill's actual text doesn’t directly censor TikTok or its users, it still has the ultimate effect of doing so."There's no denying that it would do just that," said Jenna Leventoff, senior policy counsel at the American Civil Liberties Union. "We strongly urge legislators to vote no on this unconstitutional bill."The bill’s primary mechanic – setting up a choice for TikTok that could lead to a ban – is really a sleight of hand that courts will see through instantly, according to First Amendment experts.Ken White, a First Amendment litigator at the law firm Brown White & Osborn, said courts can and do look at whether the functional effect of a law is to stifle speech, not just what the text of the law says. Lawmakers may try to say the bill regulates TikTok's foreign ownership, not content. But, White said, "'foreign influence' aren't magic words that get you out of First Amendment problems. It's not at all clear that Congress' fig leaf of an excuse will work."An important part of First Amendment scrutiny will be whether lawmakers could have achieved their goals through a "less restrictive alternative" to a flat-out ban, said Jameel Jaffer, executive director of the Knight First Amendment Institute at Columbia University. Passing a nationwide privacy law regulating how all companies, not just TikTok, handle Americans' data would lead to the same result without raising First Amendment concerns, he said.Video above: Breaking down TikTok security concernsSetting that aside, courts have held that Americans have a constitutional right to receive foreign propaganda, even if the U.S. government doesn’t like it.By that precedent, it would be unconstitutional for the government to ban TikTok even if it were blatantly a direct mouthpiece for the Chinese government, Jaffer said."If you give the government the power to restrict Americans' access to propaganda," he said, "then you've given the government the power to restrict Americans' access to anything the government deems to be propaganda."