The legal process is starting after lawsuits from several states - represented by California, Colorado, Kentucky and New Jersey - and is described as potentially having far-reaching consequences for Meta depending on the outcome.
The company is accused, among other things, of deliberately designing its Facebook and Instagram platforms in a way that makes children and young people dependent on them.
In her opening statements, prosecutor Megan O'Neill alleges that Meta's business model is designed to "capture users, hold them for as long as possible, harvest their data, and then hide the truth from the public."
Meta has denied the allegations and points to protective measures being implemented on the platforms.
