O'Neill says the jury will be shown how children are drawn onto platforms such as Facebook and Instagram, and how Meta "hooks them", with features that keep people on those apps and draw them back.

Meta knew a lot about children's brains, she says, and how they are constantly seeking rewards, and are so sensitive to social feedback, she says.

O'Neill says she has an internal document - which she shows on the screen - where a Meta employee looked at these aspects of the teenage brain, and then talked about how Instagram could change some features of the app.

The lawyer says Meta knew about the effects. She says its apps are addictive, and the court will also hear from a doctor about social media use contributing to an "alarming rise" in conditions such as depression.

O'Neill says the company told the US Congress, social media users and parents that "Instagram and Facebook were safe for kids".

"All the while it hid the truth," she adds.

O'Neill says the plaintiffs on this case are a group of 29 attorneys general, led by California, Colorado, Kentucky and New Jersey, adding the jury will hear from several attorneys general throughout the trial.

"This case is not about taking away Instagram", or whether social media has some benefits, O'Neill says.

"This case is about whether Meta misled the public about the risk to kids on its platforms, about whether Meta acted unfairly, and about whether Meta violated the Children's Online Privacy Protection [act]".

Megan O'Neill, Deputy Attorney General at California's justice department, has begun speaking.

She says Meta's business model can be summed up this way: "Hook the users; hold them for as long as they can; harvest their data; hide the truth from the public when making public statements."

O'Neill says this "worked especially work for kids", adding Meta designed the platform so children kept coming back to it.

Children are a "product", O'Neill says, adding Meta tracked their behaviour to sell them products and keep them "hooked".

The trial of social media giant Meta is now under way before Judge Yvonne Gonzalez Rogers, in a federal court in Oakland, California.

We'll be bringing you live updates.

Image source, LightRocket via Getty Images

Social media algorithm: A ranking system that uses information like user behaviour and post engagement to decide which posts are suggested to users in their feed and who sees which kinds of content

Infinite scroll: As the user scrolls down the social media feed the page loads more content, to which there is no distinct end

Autoplay: A feature which allows media to automatically start playing without user interaction

'Like' count: The number of accounts that have performed a "liking" interaction on a post, e.g. by clicking the "thumbs-up" button on Facebook or double-tapping a post on Instagram

Instagram Stories: A type of disappearing or post which users upload, usually as pictures or videos. They are available for other users to watch for a limited period of time before disappearing

Image source, PA Media

The US states who filed the lawsuit are not only seeking hundreds of billions of dollars from Meta, they are also demanding it makes substantial changes to Instagram and Facebook.

They claim the features are designed to keep users, mainly teenagers and children, on the platforms as often, and for as long as possible.

They want Meta to:

• implement parental verification for teenage users
• change its "dopamine-manipulating recommendation algorithms"
• remove many image filters that change one's appearance in photos
• end "autoplay" of video content
• prohibit the creation of multiple accounts
• end disappearing posts, such as Instagram Stories

All of these features are central to the current user experience on Meta's platforms.

Meta has consistently denied deliberately making its platforms addictive for young people in order to grow its user base and expand its business.

Lily Jamali
North America technology correspondent, reporting from court

I’m in the courtroom of Judge Yvonne Gonzalez Rogers, where Meta is about to go on trial. The room is packed with lawyers and journalists.

In some rows, people are squeezed shoulder to shoulder.

Among those here is Californian Attorney General Rob Bonta. His team will be spearheading this case alongside state prosecutors from Colorado, New Jersey and Kentucky.

There is a sense of anxiety in the air - this trial has been years in the making, with states having first filed their joint lawsuit back in 2023.

Both sides appear eager to get started.

Image source, Reuters

Image source, Getty Images

The attorney general of Kentucky, one of the states involved in the trial, has compared the lawsuit against Meta to the fight against tobacco companies in the 1990s.

That resulted in the four largest tobacco companies in the US settling dozens of state lawsuits that had been brought to recover billions of dollars in healthcare costs.

The Tobacco Master Settlement Agreement (MSA) was brought about in 1998 and aimed to reduce smoking among young people, including by restricting tobacco marketing and increasing the price of cigarettes.

And it worked - between 1998 and 2019, cigarette consumption in the US dropped by more than 50% while regular smoking by high schoolers dropped from 36.4% in 1997 to 6.0% in 2019, according to the National Association of Attorneys General.

Kentucky Attorney General Russell Coleman hopes the case against Meta will be equally successful.

"AGs are in the perfect position to get this done. We did it with the Tobacco Settlement in the 1990s... We'll do it again with Meta," he said.

Young adults in Washington DC have previously shared their views with the BBC on whether social media is addictive and how it impacts their daily lives.

Their reactions came after a Los Angeles jury found that Meta, which owns Instagram, Facebook and WhatsApp, and Google, owner of YouTube, intentionally built addictive social media platforms that harm young people's mental health.

Image source, Getty Images

In March, a Los Angeles jury found that Meta and Google deliberately built addictive social media platforms that harmed a young woman's mental health.

The 20-year-old woman, known as Kaley, sued Meta (owner of Instagram, WhatsApp and Facebook) and Google (owner of YouTube) over her childhood addiction to social media.

She was awarded $6m (£4.5m). Speaking at the time of the verdict, both Meta and Google said they disagreed with the verdict and intended to appeal.

Meta said teen mental health is "profoundly complex and cannot be linked to a single app", while Google said the case misunderstood YouTube as a "responsibly built streaming platform, not a social media site".

Image source, Getty Images

In addition to today's trial, Meta is currently facing thousands of lawsuits from authorities and families in the US over child safety issues.

Earlier this month, a US judge in New Mexico ordered Meta to pay another $567m (£421m) for its failure to warn the public about dangers its platforms posed to children.

The figure was in addition to $375m (£277m) in fines Meta was already ordered to pay in the case.

It marked the largest fine against the company over child safety.

At the time, Judge Bryan Biedscheid said the social media giant is a "public nuisance" akin to air pollution, saying it must put the money in a fund aimed at reducing future harms.

A spokesman for Meta said at the time: "We disagree with the ruling and will appeal."

In March, Meta also lost a landmark case in Los Angeles that found it could be held liable for building addictive platforms.

Liv McMahon
Technology reporter

Meta has consistently denied allegations that it has failed teens, including claims in this case that it deliberately designed its platforms to be addictive and breached child privacy laws.

"We strongly disagree with these allegations and are confident the evidence will show our longstanding commitment to supporting young people," a company spokeswoman said in a statement.

It has often cited numerous measures to protect young people, such as parental controls, safety features and making teen accounts private by default.

But this hasn’t stopped a groundswell of legal action in the US.

Image source, Getty Images

A group of 29 US states are claiming numerous violations by Meta of federal and state laws designed to protect children.

That includes breaches of the federal Children's Online Privacy Protection Act (COPPA) - intended to protect children under 13 years old from being targeted by businesses operating online.

The states allege Meta designed Facebook and Instagram to be addictive to children and teens, with features on the apps (such as video autoplay and Instagram Stories) made to keep them on there for as long as possible.

They claim Meta makes it difficult for young people to use the platform less - through functions like frequent notifications intended to get young people back on the apps.

The states allege the company has misled consumers about the safety of the platforms for young users.

Meta is also accused of improperly collecting and using children’s personal data while they used the company’s platforms.

Meta has consistently denied such claims. We elaborate on its response in the next post.

Liv McMahon
Technology reporter

Image source, Getty Images

The trial that begins today stems from a lawsuit filed against Meta by a coalition of US states in October 2023.

In that lawsuit, a group of attorneys general claimed the company had used addictive features to "ensnare" users, while also concealing the dangers of its platforms.

At the time, Meta was facing scrutiny after former Facebook product manager Frances Haugen testified in front of Congress that the company was aware that its products, particularly Instagram, were harming young people.

Haugen’s claims prompted an investigation by several state prosecutors, later forming the basis for the current multi-state lawsuit against Meta.

The social media giant has consistently and strongly denied allegations it failed to protect teens. But its efforts to dismiss this suit, or at least diffuse it into smaller trials, has largely failed.

Now, four of the 29 states suing the company - California, Colorado, Kentucky and New Jersey - will present their case.

Image source, Getty Images

Meta will go on trial today over claims it violated a series of federal and state privacy laws for children.

The Instagram and Facebook owner is accused of designing its platforms to be addictive to young people and violating child privacy laws.

Four states are due in court today seeking billions of dollars from Meta - it follows a lawsuit filed by 29 states in 2023 arguing the company violated child privacy laws.

The states are also demanding it makes changes to Instagram and Facebook, including changes to "like" counts and the infinite-scroll function.

Kentucky Attorney General Russell Coleman has described the case as "the largest consumer protection lawsuit in American history".

A Meta spokesperson said the company "strongly" disagrees with the allegations, insisting it has a "longstanding commitment to supporting young people".

Stick with us ahead of the trial getting under way in Oakland, California.