It is an ambitious social experiment of our moment in history — one that experts say could accomplish something that parents, schools and other governments have attempted with varying degrees of success: keeping kids off social media until they turn 16.

Critics say big questions remain not only about how the new law will be enforced, but also about whether the ban will really protect young people.

One of the world's toughest social-media crackdowns took a week to become law, after a lawmaker's wife read Jonathan Haidt.