After a regime-changing war, a state often engages in lustration—condemnation and punishment of dangerous, corrupt, or culpable remnants of the previous system—e.g., de-Nazification or the more recent de-Ba’athification in Iraq. This common practice poses an important moral dilemma for liberals because even thoughtful and nuanced lustration involves condemning groups of people, instead of treating each case individually. It also raises important questions about collective agency, group treatment, and rectifying historical injustices. Liberals often oppose lustration because it denies moral individualism and (...) ignores rule of law, and their only justifications for lustration are consequentialist ones. This article suggests that lustration may not necessarily be a problem for liberals. While group treatment might be justified on grounds of convenience and pragmatism in times of transitional justice, there are also valid moral arguments consistent with moral individualism and due process for wholesale group punishment after a war. This article offers four overlapping moral justifications, in a robust defense of the core concept of lustration that is covered by each argument. (shrink)