The events surrounding COVID-19, combined with the mandatory quarantines widely imposed in Asia and Europe since the virus outbreak, have reignited discussion of the balance between individual rights and liberties and public health during epidemics and pandemics. This article analyses this issue from the perspectives of precaution and necessity. There is a difficult relationship between these two seemingly opposite principles, both of which are frequently invoked in this domain. Although the precautionary principle encourages the use of quarantines, including mandatory quarantines, (...) and associated restrictive measures, the principle of necessity puts a break on such measures. The COVID-19 pandemic reveals once again the different interrelations between these two principles. However, the alleged conflict between the PN and the PP is based on a superficial analysis. The relation between these two principles is far more complex, as this article will demonstrate. (shrink)