2015 – An internal Meta memo estimates over 4 million users under age 13, roughly 30 % of U.S. 10‑12‑year‑olds, highlighting early awareness of under‑age activity before robust age‑verification was introduced[6][7].

2018 – Meta rolls out an Instagram daily‑limit feature and launches Messenger Kids, but internal data later show only 1.1 % of teen users adopt the limit tool, indicating limited uptake of safety measures[2].

2019 – Executives exchange emails criticizing “unenforced” age restrictions and strategizing to keep “tween” users on Instagram, revealing deliberate retention goals for minors[2].

2024 – U.S. Surgeon General Vivek Murthy urges Congress to require tobacco‑style warning labels on social‑media platforms, signaling growing governmental pressure on tech firms[8].

2025 – Plaintiff Kaley’s deposition notes she never received a clinical diagnosis of social‑media addiction, a point Meta later uses to challenge liability claims[10].

Jan 21, 2026 – Snap settles its California addiction lawsuit days before jury selection, removing itself from the pending case while Meta, TikTok and YouTube remain defendants[4].

Jan 26, 2026 – The Los Angeles bellwether trial launches against Meta, TikTok and YouTube, with senior executives slated to testify over a six‑to‑eight‑week period[8].

Jan 27, 2026 – Hours before jurors are sworn, TikTok reaches a confidential settlement, exiting the case and leaving Meta and Google as the remaining defendants[3].

Jan 27, 2026 – Jury selection begins for the Instagram‑TikTok‑YouTube trial, marking the first time these firms face a jury over alleged addictive design[12].

Feb 18, 2026 – Meta CEO Mark Zuckerberg testifies, stating he “wishes age‑verification improvements had arrived sooner” and acknowledging the company’s lag in detecting under‑13 users[15].

Feb 18, 2026 – Zuckerberg also tells the jury that “research on teen ‘addiction’ was external” and that teen users generate less than 1 % of Meta’s ad revenue, downplaying the platform’s profit motive[2].

Feb 19, 2026 – During five hours of questioning, Zuckerberg claims lawyers are “mischaracterising” internal communications about teen usage, while internal documents reveal past “Time +10 %” goals that the company later abandoned[2][11].

Feb 22, 2026 – Instagram head Adam Mosseri testifies that a teen scrolling up to 16 hours a day may be “problematic,” though he stops short of labeling it a clinical addiction, echoing arguments once used by tobacco firms[5].

Feb 26, 2026 – Twenty‑year‑old Kaley files a federal lawsuit against Meta and Google, alleging “nonstop Instagram use, YouTube autoplay, and resulting mental‑health issues” that began when she was six and nine respectively[1].

Feb 27, 2026 – Plaintiff KGM testifies that she used Instagram and YouTube “all day long” from childhood, describing “rush” notifications, bought likes, and a lifelong pattern of anxiety, depression, and suicidal thoughts[10][13].

Feb 27, 2026 – The trial is slated to run until mid‑March, with a verdict expected by late March, potentially setting precedent for 1,500+ similar suits nationwide[1].

Summer 2026 (planned) – Two additional Los Angeles bellwether trials are scheduled, and a federal trial for school‑district plaintiffs will begin in June in Oakland, expanding the litigation landscape[12].

2026 onward (ongoing) – Over 40 state attorneys general have sued Meta, TikTok faces suits in more than a dozen states, and countries such as Australia have banned users under 16, while the UK, Denmark, France, and Spain consider similar restrictions[8][2].

2026 (parallel) – A separate New Mexico state case accuses Meta of facilitating sexual exploitation of minors through its algorithms, a trial that could influence outcomes in the Los Angeles proceedings[9].