The health of the planet and its life forms are under threat from anthropogenic climate change, pollution and biodiversity loss, and the extreme weather events, heatwaves and wildfires that accompany them. The burgeoning field of planetary health studies the interplay between humanity and the Earth's biosphere and ecosystems on which human health depends. Scholarship on law from a planetary health vantage point remains scarce. This article fills this gap by delineating the conceptual building blocks of a planetary health law, which, in its latent form, is dispersed across various hard and soft sources of international environmental law and global health law that converge on the right to a healthy environment, and, to a lesser extent, rights of nature emerging in various domestic jurisdictions. It elucidates how the fragmented regimes of international environmental and global health law could be developed in more coherent ways, driven by an overarching concern for the integrity of the planetary foundations of life.

International comparisons of the effectiveness of coronavirus disease 2019 (COVID-19) non-pharmaceutical interventions (NPIs) based on national case and mortality data are fraught with underestimated complexity. This article calls for stronger attention to just how extensive is the multifactorial nature of national case and mortality data, and argues that, unless a globally consistent benchmark of measurement can be devised, such comparisons are facile, if not misleading. This can lead to policy decisions and public support for the adoption of potentially harmful NPIs that are ineffective in combating the COVID-19 pandemic and damaging to mental health, social cohesion, human rights and economic development. The unscientific use of international comparisons of case and mortality data in public discourse, media reporting and policymaking on NPI effectiveness should be subject to greater scrutiny.

This paper brings a constitutional economics perspective to bear on the World Health Organization (WHO), the flagship United Nations intergovernmental health organisation, which is obligated by its Constitution to achieve ‘the highest possible level of health’ for the world's peoples. The WHO has in the seven decades of its existence used its formidable legislative powers only sparingly. It has been widely chided for being weak in regional coordination and unresponsive to transnational emergencies like the West African Ebola outbreak of 2014–2016. In 2020, it found itself at the centre of the COVID-19 pandemic and in the middle of the Sino-American geopolitical tug-of-war. This paper traces the discordance between the Constitution's stated purposes and the actual track record of the WHO not back to its organisational culture nor to weak leadership but to the design of the Constitution itself. It analytically distinguishes the Constitution's expressive from its instrumental halves, and shows that, whilst the former embodies a ‘constitutional moment’ of international health solidarity right after the Second World War, the latter embodies a reserved and limited delegation from member-states that are jealous of their sovereignty.