Biodiversity laws around the world differ, but, at their core, these laws promote the fundamental objective of preventing environmental decline and species extinctions. A variety of legal mechanisms have been implemented in domestic laws around the world to achieve this objective, including protection for habitat, environmental impact assessments and threatened species recovery plans. In many jurisdictions, if these mechanisms fail to protect a species, it may be legally declared extinct, or added to a formal list of those that have been lost. This article examines the conservation purpose and legal implications for laws about extinction. A legal power to recognise a species as extinct has the potential to foster ambition, transparency and rigorous measurement of progress against conservation goals. However, in practice, efforts to prevent extinction are applied selectively. Without an obligation to learn from extinctions, recognition of species extinctions in law may have perverse effects, or no effect at all. This article proposes a conceptual model for the role of law in relation to extinctions, highlighting opportunities to improve legal frameworks to achieve more productive and positive conservation outcomes, even as climate change and other pressures drive many more species towards extinction.