Roughly a decade has passed since experts began to appreciate that social media may be truly hazardous for children, and especially for teenagers. As with teenage smoking, the evidence has accumulated slowly, but leads in clear directions. The heightened rates of depression, anxiety, and suicide among young people are measurable and disheartening. When I worked for the White House on technology policy, I would hear from the parents of children who had suffered exploitation or who died by suicide after terrible experiences online. They were asking us to do something. The severity and novelty of the problem suggests the need for a federal legislative response, and Congress can’t be said to have ignored the issue. In fact, by my count, since 2017 it has held 39 hearings that have addressed children and social media, and nine wholly devoted to just that topic. Congress gave Frances Haugen, the Facebook whistleblower, a hero’s welcome. Executives from Facebook, YouTube and other firms have been duly summoned and blasted by angry representatives. But just what has Congress actually done? …