Social media age-gating: does it reduce harm? UK Online Safety Act, EU Digital Services Act and Australia’s social media ban

This paper evaluates whether social-media age-gating – Australia’s under-16 ban – can reduce harm relative to the UK Online Safety Act and the EU Digital Services Act. Bringing clinical, developmental, and behavioural evidence into a legal analysis, it shows that risk is heavy-tailed and co-produced: a minority with pre-existing vulnerabilities experience severe outcomes amplified by platform affordances (visibility, metrics, ranking, availability). Because ‘time on platform’ is endogenous – simultaneously predictor, mediator, and outcome – simple dose–response claims fail, and exclusion by age mostly postpones first contact while leaving the state–behaviour–design loop intact. The paper argues that age-gating alone is unlikely to change whether severe cases occur; it changes when they appear. It proposes a two-pillar response: (1) investment in adolescent mental-health capacity (school-embedded early intervention, anti-bullying, family support, offline alternatives, algorithmic literacy) and (2) targeted design duties (default night-mode, diversity injections in sensitive niches, audited tail-focused studies), given legal force based on the DSA as the template.