This short article examines whether China has incurred responsibility for violating a general due diligence obligation in customary international law or specific obligations under the WHO’s International Health Regulations and the WHO Constitution in a context of Covid-19. It is submitted that due diligence is merely a notion to describe a primary obligation, or a standard by which a particular primary obligation is assessed. It cannot serve as the basis for holding a State responsible. Regarding the WHO regime, actions taken by China after December 2019 neatly fit into the staggered requirements of Articles 6 and 7 of the International Health Regulations, which do not set out clear standards for the evaluation of a health emergency. On a more general level, we reflect upon the role of international law in global pandemic control and caution against the politicization of international health law.