Thune is closing things up by again bringing up concerns about conservative bias, and asks Facebook to err on the side of allowing speech.

Grassley jumps in to say that he spoke with another CEO of another platform yesterday who admitted to him that he was a liberal. Grassley is kind of rambling about media bias and partisanship.

It seems that Grassley is calling on Zuckerberg to reduce cynicism about government institutions in his spare time. “I hope that everyone will do whatever they can to help increase respect for government.”

Zuck remains silent.

“I’m sorry you had to listen to me,” Grassley adds. The hearing is adjourned.

Young: If we created a stronger property right that states users own their data – or a stronger opt-in rule – would you have to change Facebook fundamentally?

Zuck: It depends on the details.

Zuck says that Verizon or other ISPs should not be able to have knowledge of content, but Facebook and other platforms can and should.

False alarm on the final questioner: We now have Senator Todd Young, who notes that there isn’t a single senator who doesn’t use Facebook to communicate with constituents.

Tester: You said multiple times during this hearing that I own the data. I’m going to tell you that I think that sounds good, but in practice you’re making $40bn a year, I’m not making money on it. It feels like you own the data... Could you give me some idea on how you can honestly say it’s my data?

Zuck: When I say it’s your data, what we mean is that you have control over how it’s used on Facebook. You clearly need to give Facebook a license to use it otherwise the system doesn’t work.

Tester: The fact is the license is very thick, maybe intentionally so.

We’re getting close to the end, with the final round of questions from Senator Jon Tester.

Gardner: Has Facebook ever been hacked?

Zuckerberg: Yes, but not that seriously. He says there was a malware attack in 2013.

Garder is now asking about Facebook’s ability to track the articles people read on non-Facebook sites (such as this one!). Garder asks whether users understand what is happening, and Zuck stumbles toward saying yes, which is a tough claim to make.

Zuck says the social context of having the “Like” button is a clue, but I would guess that most users don’t know exactly how Facebook uses those ubiquitous Like buttons.

Here’s a ProPublica explainer of how that works.

Senator Cory Gardner is now reading parts of the terms of service related to account deletion, which mentions that backup copies may persist after an account is deleted for some amount of time.

Zuckerberg says he doesn’t really know how long those backup copies stick around, but seems confident that they are actually deleted.

Cortez Masto is reading out various aspects of the 2011 FTC consent decree. What did you actually do in response to the decree?

Zuckerberg: We established a robust program...

Cortez Masto: Had you addressed the issues then, had you done an audit, you would have known that this type of data was being shared. That’s what I’m saying it’s time for the change.

Senator Catherine Cortez Masto: “Stop apologizing and let’s make the change. It’s time to really change the conduct.”

Senator Shelley Moore Capito: Does Facebook get a cut of advertisers’ sales?

Zuck: No.

Now Zuck is kind of explaining the ad auction, which is very confusing territory. “We get paid when the action the advertiser wants to happen happens.”

Senator Maggie Hassan: “There’s clearly tension between your bottom line and what’s good for your users.”

Hassan says that she believes that Zuckerberg believes that he will never prioritize advertisers over users, but it’s a for profit company, and he has an obligation to his shareholders.

Senator Ron Johnson: Do you have any idea how many users actually read the terms of service?

Zuck says probably not a lot of people, but he doesn’t know. Says that everyone has the “opportunity” to read them, and that it doesn’t change the fact that they’ve consented to it.

Considering that Facebook (and any other publisher) can tell how many seconds a user stays on any individual webpage, I see no reason why Facebook couldn’t provide precise analytics of how many people have read the terms of service and how deep into the document they got.

John Kennedy: Can somebody call you up and say I want to see John Kennedy’s file?

Zuck: Absolutely not.

Kennedy: Not can you do it. Could you do it?

Zuck: Technically someone could do that but it would be a massive breach.

Senator John Kennedy: I don’t want to regulate Facebook but god help you I will... I say this gently: your user agreement sucks. You can spot me 75 IQ points. The purpose of that user agreement is to cover Facebook’s rear end, it’s not to inform your users about their rights. You know that and I know that. I’m going to suggest that you go home and rewrite it.

Harris says that Facebook’s response to written questions from the last hearing “evasive and some were frankly non-responsive”.

She says she’s going to submit more questions.

Senator Kamala Harris sets the tone for her questioning by listing all the questions Zuckerberg has dodged so far: “During the course of this hearing, you’ve been asked several critical questions for which you don’t have answers. Those questions include whether Facebook can track activity after a user logs off, whether Facebook can track you across devices, who is Facebook’s biggest competition, whether FB stores up to 96 categories of users information. Whether you knew Kogan’s terms of services, and another case in point related to Cambridge Analytica, is that you became aware in December 2015 that Kogan misappropriated data from 87m users. That’s 27 months ago. However, a decision was made not to notify.”

The former prosecutor is now quizzing Zuckerberg on the decision making process that led Facebook NOT to notify users: “So my question is, did anyone at Facebook have a conversation at the time that you became aware of this breach wherein the decision was made not to contact the users?”

Zuckerberg: I don’t know if there were any conversations at all at Facebook... I don’t know what other people discussed.

Zuck says he doesn’t remember having a conversation where Facebook decided not to inform the users. Says that in retrospect it was a mistake.

Tillis: I’m a proud member of Facebook... If you don’t want to share something don’t share it... It’s a free app. Go on there and find out what you signed up there.

Finally, Tillis gets around to a question: When you were developing this thing in your dorm, how many people did you have on your regulatory affairs department?

Tillis’s point is that regulation could kill the next Facebook in its cradle. He never actually gave Zuckerberg a chance to respond.

And we’re back!

Senator Thom Tillis is kicking off by discussing Zuckerberg’s personal Facebook feed. Then he pivots to discuss the Obama campaign’s use of a Facebook app in 2012, and suggests that this activity needs to be part of the conversation related to Cambridge Analytica.

This live blogger is struggling to keep up to date with her bingo card, but here’s an update to tide you over during the break.

Senator Dean Heller: Have you ever drawn the line on what kind of data you will sell to advertisers?

Zuckerberg jumps on Heller’s misstatement – that Facebook doesn’t “sell” data – and dodges the question of whether Facebook would ever draw a line on what kind of data it collects or uses to target advertisers.

Heller: Do you record the contents of our calls?

Zuck: I don’t believe we’ve ever collected the content of phone calls.

Heller: Do you believe you’re more responsible with our data than the US government?

Zuck: Yes.

Heller: Do you think you’re a victim? Do you think you’re company is a victim.

Zuck: No. We have a responsibility to protect anyone in our community.

Heller: Do you consider the 87m to be victims?

Zuck: Yes... That happened and it happened on our watch.

Booker: “You are an industry that lacks diversity.” Asks whether Facebook would open its platform to civil rights organizations to audit what’s happening with discrimination.

Zuck: That’s a good idea. Let’s follow up.

Booker: Raises concern about use of Facebook by law enforcement to surveil groups like Black Lives Matter. Will you ensure that your platform isn’t used to surveil and undermind the work of civil rights activist?

Zuck: Yes. Notes that Facebook only supplies information to law enforcement with a subpoena or warrant.

Yesterday, CNN reported that one of the largest “Black Lives Matter” pages on Facebook was actually being run by a white Australian man.

Senator Cory Booker: “We’ve seen how technology platforms can be used to double down on discrimination.”

Booker is talking about all the ways that Facebook’s ad targeting tools can and have been used to publish discriminatory advertisements in violation of civil rights legislation, despite Facebook’s promise to reform.

Booker mentions that Facebook’s reforms have included requiring self-certification by advertisers that they aren’t being discriminatory, but notes that self-certification didn’t work with Cambridge Analytica.

Zuckerberg again brings up artificial intelligence tools and a desire to become more “proactive,” but adds: “I’m not happy with where we are.”

This is a weird line of questioning. People rightly lay a lot of responsibilities at Zuckerberg’s door, but passing legislation is actually Congress’s job.

Senator Tom Udall asks if Zuckerberg is going to be an advocate for the Honest Ads Act.

Zuckerberg: Our team is certainly going to work on this.

Udall: I’m talking about you.

Zuckerberg: Well, Senator, I try not to come to DC.

Zuckerberg says that being responsible for the content on the platform is not incompatible with being a tech company rather than a publisher.

Sullivan: Which are you? Are you a tech company? Or are you the world’s largest publisher?

Zuckerberg: I view us as a tech company... I agree that we’re responsible for the content, but we don’t produce the content.

Sullivan: “Do you think Facebook is too powerful?”

Zuckerberg: “We need to have a conversation about the right regulation.”

Sullivan: “Regulation can cement the dominant power... One of my biggest concerns is that the next Facebook, the guy in the dorm, that you are becoming so dominant that we won’t be able to have the next Facebook.”

Zuckerberg: [doesn’t mention his aggressive acquisition of rival startups]

A moment of levity when Senator Dan Sullivan tries to get Zuckerberg to say that Facebook could only have been built in America.

Zuck doesn’t bite, noting that China has a lot of great tech companies.

Sullivan: You’re supposed to say yes.

Hirono brings up the fact that discriminatory advertising is still possible on Facebook, despite its promises.

Just last month, fair housing groups filed a federal lawsuit over this.

Hirono asks why they haven’t managed to fix this yet.

Zuck says that the company relies a lot on users to flag content that is discriminatory, but as of now, users can’t actually tell the precise targeting that an advertiser is using.

Senator Mazie Hirono brings up Immiration and Customs Enforcement (Ice) and its interest in using social media data to profile immigrants. She asks: Does Facebook intent to cooperate with this ‘extreme vetting’ process to help Ice target people for deporation?

Zuck says that Facebook would not proactively cooperate with Ice, but does comply with legal requests for information.

Flake: Do you believe Russia or China have harvested Facebook data and have profiles on users?

Zuck: We have kicked off an investigation. “I imagine we’ll find some things.” Says they don’t have specific knowledge of efforts by other nation states but says they assume other countries will try to abuse the system.

Senator Jeff Flake: What are you doing to prevent oppressive governments from going after dissenters?

Zuckerberg: We’re hiring more people who speak more languages, working with civil society groups to identify leaders of hate speech, and making product changes for some countries.

These product changes came up earlier in response to Leahy’s questions about Myanmar, but Zuck didn’t specify what they were. Now he says they may have to do with news literacy and fact checking.

Markey is now asking Zuckerberg to support a privacy bill of rights for children.

Zuck: We already do stuff. [paraphrase]

Markey: I’m talking about a law... Do you believe we need a law to protect children?

Zuck: I’m not sure we need a law.

Markey: I couldn’t disagree more.

Markey says we’re leaving children vulnerable to “rapacious” exploiters of their information.

The Observer’s Carole Cadwalladr, who broke the revelations about Cambridge Analytica’s use of Facebook data, points out that Facebook’s stock has soared during Mark Zuckerberg’s testimony ...

Senator Edward Markey: Would your support a law that says Facebook and and any other company that gathers information has to get affirmative permission before it can be reused for other purposes?

Zuckerberg: In general I think that idea is right.

Markey: But would you support legislation?

Zuckerberg: As a principle, yes, but the details matter a lot.

Sasse: Do you hire consultants to tell you how to tap into dopamine feedback loops to keep people addicted?

Zuckerberg: No.

Sasse didn’t ask whether they hire experts in the field directly.

Sasse is now talking about social media addiction. As a dad, do you worry about social media addition as a worry for American’s teens?

Zuck: “This is certainly something that I think any parent thinks about – how much do you want to your kids to use technology.”

Zuck says that if you’re using the internet to engage with other people, it’s good, but if you’re using the internet to passively consume content, it’s not that good.

Sasse is concerned that Facebook’s hate speech guidelines are based on feelings of unsafety and offense, which he says could result in the censorship of anti-abortion advocates not being allowed to speak against abortion.

Senator Ben Sasse: The conceptual line between mere tech company and content company is difficult.

“Facebook may decide it needs to police a whole bunch of speech that I think America may be better off not having a single company police... Can you define hate speech?”

Coons: “Why do you shift the burden to users to flag inappropriate content and get it taken down?”

Zuckerberg points out that the company started in a dorm room with few resources, a response that rings hollow 2,000,000,000 users and hundreds of billions of dollars in revenue later.

Coons: “At the end of the day, policies aren’t worth the paper they’re written on if Facebook doesn’t follow them.”

Coons mentions that he found accounts impersonating him just this morning, and only got them taken down immediately because he’s a senator.

Senator Chris Coon is raising concerns about ad targeting, bringing up ProPublica’s reporting that Facebook ad targeting tools could be used to publish racially discriminatory ads in violation of federal civil rights law.

Coons says there’s tension between Facebook’s promises for reform and history of inadequate action.

Fischer: Is Facebook about feeling safe? Or actually being safe?

Zuckerberg says that Facebook is actually safe, as proven by the fact that he and his family use it all the time.

Of note, late last week TechCrunch revealed that Facebook had set up special tools to enhance the privacy of Zuckerberg and other executives that were not made available to regular users.

Zuckerberg: There are two broad categories... content that a person has chosen to share and that they have complete control over... The other category is data that is connected to making ads relevant. You have complete control over both.

Fischer: How much of it do you store? Everything that we click on? Is that stored somewhere?

Zuck: Yes, we do store data.

Senator Deb Fischer: How many categories of data do you collect for all 2bn users?

Zuckerberg: [acts confused]

Brian Schatz: Are you open to the idea of an information fiduciary?

Zuck: It deserves consideration.

Schatz asks whether the content of WhatsApp messages informs advertisements.

Zuck says no – WhatsApp has end to end encryption, so the company doesn’t know the content of your messages.

However, as we learned earlier today, third-party apps like Kogan’s were able to scrape messages from Facebook’s Messenger service.

Schatz is distinguishing between data that you share and data about your behavior that Facebook infers.

Zuck: “You don’t have to put anything up in the first place if you don’t want.”

Senator Brian Schatz: “People have no earthly idea what they are signing up for. Can you explain to users in plain language what they are signing up for?”

Mike Lee: Give me two examples of ways data is collected by Facebook in ways people might not know?

Zuckerberg: I would hope that what we do with data is not surprising.

This gets to the core obfuscation that Zuckerberg is relying on. People do have control over what they publish, but not what Facebook collects.

Zuck now addresses this second kind of data, which Zuckerberg calls “data we collect in order to make the advertising experience better”. He claims people still have control over this.

Zuck: People chose to share information with an app developer.

This is true only for about 300,000 of the 87m people affected. The vast majority simply chose to be friends with people who chose to download the app.

Senator Mike Lee, a Republican from Utah, is returning to Ted Cruz’s line of questioning about political bias in Facebook’s content moderation.

Lee: Would you put your thumb on the scale as far as the viewpoint of the content posted?

Zuck: No.

Whitehouse is now calling attention to the difficulty Facebook will face in verifying the actual source of funds for political advertisements, noting that a Russian operation could simply use a Delaware corporation and mailing address.

Zuckerberg concedes this is true.

Whitehouse asks about how Facebook’s bans actually work.

Zuckerberg says that Cambridge Analytica, SCL, and AggregateIQ are all banned. But he says that he doesn’t believe the company is banning individual leaders of the companies.

Whitehouse: Are the terms of service take it or leave it? Or can individuals negotiate?

Zuckerberg says yes, the terms are not negotiable, but again mentions the “controls” that users have over what they publish.

We’re on a short break. If you’re following along from home, here’s the bingo card I made yesterday.

Senator Ted Cruz is focusing his questioning on whether or not Facebook is guilty of liberal bias against conservative content, a subject of much suspicion among Republicans since a 2016 Gizmodo report alleging that moderators were suppressing conservative news.

Zuckerberg defended the platform’s political neutrality, despite the fact that its based in liberal Silicon Valley.

Cruz: “Why was Palmer Luckey fired?”

Zuckerberg: “It was not because of a political view.”

Senator Richard Blumenthal is pushing hard on Zuckerberg and Facebook’s statements that Aleksandr Kogan deceived the company when he harvested 50m users’ data.

Blumenthal has a copy of the terms of service that Kogan used, and points out that they included commercial use of the data.

“Facebook was on notice that he could sell that user information,” Blumenthal says. He says Facebook engaged in “willful blindness” and was “heedless and reckless”. He also asserts that the Terms of Service Kogan was able to user were a violation of Facebook’s FTC consent decree, which Zuckerberg denies.

“We’ve seen the apology tours before. You have refused to acknowledge even an ethical violation to report this violation of the FTC consent decree,” Blumenthal says. “My reservation about your testimony today is that I don’t see how you can change your business model unless there are specific rules of the road. Your business model is to maximize profit over privacy. I have no assurance that these kids of vague commitments are going to produce actions.”

Senator John Cornyn brings up Facebook’s old motto of “move fast and break things”.

“The broader mistakes we made were not taking a broad enough view of our responsibility,” Zuckerberg says.

Cornyn asks pointedly about the old line that Facebook and the like are “neutral platforms”.

Zuck replies: “I agree that we are responsible for the content.”

Senator Dick Durbin began his questioning by probing at Zuckerberg’s own sense of his personal privacy.

“Would you be comfortable sharing with us the name of the hotel you stayed in last night?” Durbin asked.

“No.”

If you messaged someone last week, will you share that with us now?

No.

Durbin says that this gets to the core of the issue of privacy. Zuckerberg again raises the point that people “choose” to “share” information with Facebook, which obfuscates the fact that Facebook can infer what hotel you stayed in last night without you ever “sharing” that information in a specific post.

Senator Patrick Leahy presses Zuckerberg hard on its role in the ethnic cleansing of Rohingya from Myanmar, holding up a blowup image of a post calling for the death of a Muslim journalist.

“That threat went straight through your detection, spread very quickly, and then it took attempt after attempt after attempt and the involvement of civil society groups” to get Facebook to take it down, Leahy said.

“What’s happening in Myanmar is a terrible tragedy and we need to do more,” Zuckerberg began, but Leahy interrupted.

“We all agree its terrible,” Leahy said, before calling on Facebook to do much more.

Zuckerberg says the company is hiring “dozens” more Burmese language content reviewers, taking down accounts of “specific hate speakers”, and putting together a special product team that will produce some kind of “specific product changes” in Myanmar that he did not specify.

One of the great things about this hearing is that Senators are asking very basic questions about how its service works.

Senator Roger Wicker mentions that he’s heard that Facebook can track internet browsing even after someone has logged out of Facebook, and asks whether that’s true.

Zuckerberg tried to deflect, suggesting that staff would follow up, but then was pushed to concede that Facebook does indeed track cookies.

Senator Maria Cantwell’s line of questioning started with Palantir and wound its way to European data privacy law.

Along the way, Cantwell got Zuckerberg to commit to finding out whether Facebook employees worked directly with Cambridge Analytica employees during the Trump campaign.

Senator Orrin Hatch, a Republican from Utah, is offering a basic defense of Facebook’s business model, noting that nothing in life is free. He asks Zuckerberg what kind of regulations Facebook would support.

Zuckerberg mentions that it’s important that data policies be understandable for people – which feels like a non sequitur – and warns that too much regulation on issues like facial recognition technology could result in America “falling behind” China and other countries.

Thune also asked about Facebook’s ability to manage hate speech. Zuckerberg discusses artificial intelligence and increased staffing for moderation.

“There’s a higher error rate than I’m happy with,” he says.

Senator Bill Nelson is questioning Facebook’s advertising model, and the use of personal information for targeting individuals. He seems annoyed that Facebook would hypothetically charge users for an ad-free experience, but Zuckerberg points out that Facebook does not offer a paid version, and apparently has no plans to.

Zuckerberg says the advertising model is “most aligned with our mission” because it allows the company to offer the service for free.

Grassley asks how many other instances of improper data transfer have occurred.

Zuckerberg replies that Facebook is currently doing an audit to find out.

Have you ever required an audit before? Grassley asks.

Zuckerberg says that the company is going to be more “proactive” going forward.

Why doesn’t Facebook disclose to users all the ways their data might be used?

Zuckerberg responds that users can control who sees their posts, which is not exactly the same thing.

Grassley also queries why Facebook’s data policy isn’t more explicit.

“If you make it long and spell out all the detail, then you’re probably going to reduce the number of people who will read it,” Zuckerberg says.

Senator Bill Nelson, ranking member of Commerce, Science & Transportation, begins his remarks with a blunt wakeup call directly to Zuckerberg: “If you and other social media companies do not get your act together, none of us are going to have any privacy anymore.”

“If Facebook and other online companies will not or cannot fix the privacy invasions, then we are going to have to,” Nelson added. “We, the congress.”

Earlier, Senator Grassley mentioned that the Judiciary committee plans to hold a separate hearing with Cambridge Analytica.

Senator John Thune, the Republican chairman of the Commerce, Science and Technology committee, is getting started by going straight to the heart of Facebook’s business model – free service in exchange for personal data.

“For this model to persist, both sides of the bargain need to know what’s involved,” Thune said. “I’m not convinced Facebook’s users have the information they need to make decisions.”

Thune went on to say that Congress’s willingness to allow the tech industry to self-regulate “may be changing.”

Senator Chuck Grassley is opening the hearing, which he calls “unique” thanks to its size and breadth.

Forty-four senators will get 5 minutes each to question Zuckerberg, who is wearing a pale blue tie.

“That may not seem seem like a large group by Facebook standards,” Grassley said of the assemblage of so many senators, “but it is significant for the US senate.”

Many senators have arrived in the hearing room, including Ted Cruz, a Republican from Texas and former presidential candidate.

It will be interesting to see whether Cruz mentions his own involvement in this saga: When the Guardian first reported on the Facebook data harvest in December 2015, it was because Ted Cruz’s presidential campaign was using it, via Cambridge Analytica. Read the original report here.

While we wait for the hearing to begin, here’s a preview of what Zuckerberg will say, based on his prepared testimony.

“Facebook is an idealistic and optimistic company,” his statement reads. “But it’s clear now that we didn’t do enough to prevent these tools from being used for harm as well. That goes for fake news, foreign interference in elections and hate speech, as well as developers and data privacy. We didn’t take a broad enough view of our responsibility, and that was a big mistake. It was my mistake, and I’m sorry. I started Facebook, I run it, and I’m responsible for what happens here.”

The hearing was scheduled to begin at 2:15pm eastern, which has just passed. The delay is due to a Senate vote, according to Reuters.

Meanwhile, the hearing room is packed with reporters, a handful of activists from Code Pink, and, according to New York Times reporter Kevin Roose, an actual Russian troll.

“Congress is theatre,” former Obama administration official Ari Ratner told my colleague Olivia Solon, for her preview of today’s hearing. “More than what they are going to want to learn [about the data lapses], they are going to want to inflict pain.”

The appetite for public humiliation is obviously there. Senator Chris Coons, a Democrat from Delaware and member of the judiciary committee, tweeted early Tuesday that he had discovered multiple fake Facebook accounts impersonating him.

Coons’ apparent pique – “on today of all days” speaks of a certain amount of high dudgeon – is indicative of the attitude many citizens, regulators, and lawmakers feel toward the company that has monetized our identities and intimate relationships: this is personal.

And yet, in order to draw blood, lawmakers will have to actually pass legislation reining in Facebook’s power. It’s hard to imagine that happening with this Congress.

You can read the rest of our preview of today’s hearing here.

Welcome to the Guardian’s live coverage of Mark Zuckerberg appearance before the US Congress. Today, Zuckerberg will answer questions from a joint hearing of the Senate judiciary and commerce, science and transportation committees. Tomorrow he will run the gauntlet again before the House committee on energy and commerce.

The hearing will be live-streamed here.

Zuckerberg’s appearance before Congress – his first, despite having been at the helm of one of the most powerful companies in history for 14 years – is the result of powerful public pressure in the wake of Facebook’s massive data harvesting scandal. Last month, the Observer revealed that the Facebook data of tens of millions of Americans was harvested and improperly transferred to the political consultancy Cambridge Analytica.

Despite initially downplaying the significance of the reporting, Facebook has subsequently apologized, promised to change, and acknowledged that as many as 87m people were affected. The company has also announced a flurry of reforms, from revised terms of service to updated privacy settings, stricter rules for political advertisers and a new data leak bounty.

Today’s hearing is ostensibly about “social media privacy and the use and abuse of data” – but with as many as 44 senators expected to take their turn grilling the CEO, we are likely in for a wide-ranging airing of grievances about the company and its unprecedented power.

Last year, when Congress held hearings about the use of social media by a Russian influence operation, Zuckerberg sent Facebook’s general counsel to testify while he and his family dressed up as characters from Where The Wild Things Are for Halloween.

This time around, Zuckerberg wasn’t able to dodge the bullet. Let the wild rumpus start!