2015 – Internal memo estimates over 4 million Instagram users under 13, about 30 % of U.S. 10‑12‑year‑olds, showing early awareness of under‑age usage[4][5].

2018 – Meta launches Instagram daily‑limit feature and Messenger Kids, its first public tools to curb teen screen time, yet internal data later reveal only 1.1 % of teen users adopt the limit[1].

2019 – Executives exchange emails criticizing “unenforced” age limits and strategizing “tween” retention, while Meta commissions an external Instagram study on teen usage, indicating a focus on growing younger audiences[1].

Dec 2019 – Instagram begins requiring birth‑date entry for new accounts; the policy expands to existing accounts in Aug 2021, but many under‑13 users still join unchecked[4][5].

2022 – Internal “stretch goal” sets a target to raise average daily Instagram use from 40 minutes (2023) to 46 minutes by 2026, reflecting a deliberate push to increase youth engagement[4].

2024 – Zuckerberg delivers a congressional apology acknowledging Meta’s role in teen mental‑health harms, while Surgeon General Vivek Murthy calls for tobacco‑style warnings on social‑media platforms, heightening regulatory pressure[6].

Jan 21, 2026 – Snap settles a California social‑media addiction lawsuit days before trial, removing itself as a defendant while other firms remain in the case[3].

Jan 26, 2026 – The Los Angeles bellwether trial launches, with jury selection slated for Jan 27 and senior executives from Meta, TikTok and YouTube slated to testify over alleged addictive design[6].

Jan 27, 2026 – Jury selection begins and the trial officially starts, marking the first time Instagram, TikTok and YouTube face a jury over youth‑addiction claims; plaintiffs allege the platforms use slot‑machine‑style techniques to hook teens[9].

Jan 27, 2026 – TikTok reaches a confidential settlement hours before jurors are sworn, exiting the case while Meta and Google remain defendants[2].

Jan 27, 2026 – Over 40 state attorneys general have sued Meta, and a federal bellwether trial is scheduled for June in Oakland, underscoring the nationwide scope of the litigation[9].

Feb 18, 2026 – Zuckerberg testifies that he wishes age‑verification tools had arrived sooner, admits past “time‑spend” goals, and says the company now relies on content‑behavior signals to detect under‑13 users[11].

Feb 18, 2026 – A parallel New Mexico state case proceeds in Santa Fe, accusing Meta of facilitating sexual exploitation of minors through its algorithms, a case that could influence other state lawsuits[7].

Feb 19, 2026 – Zuckerberg tells the jury that scientific research has not proven a causal link between social‑media use and mental‑health injury, and references internal feedback urging him to sound “authentic, direct, human, insightful and real”[8].

Feb 19, 2026 – He emphasizes that “less than 1 %” of Meta’s ad revenue comes from minors and argues that Instagram’s “beauty” filters, though flagged internally as potentially harmful, remain available under a free‑expression rationale[1].

Feb 19, 2026 – Plaintiffs present internal Instagram target “Time +10%” and a “stretch goal” to surpass TikTok, while Zuckerberg claims the company has shifted to a “utility and value” focus and abandoned time‑spending metrics[5].

Feb 21, 2026 – A landmark U.S. trial begins against Meta and YouTube, expected to run until late March, with two additional Los Angeles trials slated for the summer, highlighting the expanding legal battle over teen mental‑health impacts[10].

2026 (future) – The trial’s outcome could set precedent for roughly 1,500 related lawsuits and trigger billions in liability; Australia’s under‑16 ban remains in effect and the UK, Denmark, France and Spain are considering similar restrictions[1].

June 2026 (planned) – A federal bellwether trial for school‑district plaintiffs is set to start in Oakland, potentially creating a national benchmark for social‑media addiction litigation[9].