States all over the world have reacted to COVID-19 with quarantines of entire cities, provinces, and even nations. Previous studies and preliminary evidence from current lockdowns suggest that emergency measures protecting the public’s physical health by dislocating individuals, families, and social networks could well be causing a devastating public health crisis of mental ill-health in the months and years to come. This article is the first to take a public mental health ethics perspective in examining these lockdowns, the lodestar of which is the right to mental health, rooted in the concept of human dignity. Even the strictest lockdowns are not necessarily unethical but are prone to damage mental health disproportionately, with vulnerable and disadvantaged populations being at particular risk.