During the COVID-19 pandemic, authorities have imposed various social restrictions on a massive scale. This Viewpoint discusses current issues about the legality of restrictions and current knowledge about how to prevent the spread of Sars-Cov-2. Although vaccines are already available, other basic public health measures are needed to suppress the transmission of SARS-CoV-2 and reduce the COVID-19 related mortality: isolation, quarantine, and wearing of face masks. This Viewpoint shows that the emergency measures during a pandemic are important for protecting the public's health, but they may only be legitimate if they are based in law, are in accordance with medical knowledge, and aim to limit the spread of infectious agents. We concentrate on a legal obligation to wear face masks as it became a most recognizable symbol of the pandemic. It was also one of the most criticized obligations and the subject of divergent views.

The purpose of this paper was to prove that the standards for environmental friendliness set out by international law require the states to carry out Health Impact Assessment (HIA) before implementation of public or private investments having a potential human health impact even if national legal systems do not require it. The analysis of both soft international law and treaty law, as well as the case-law of international courts and tribunals show that Environmental Impact Assessment (EIA) is the international law ius cogens. At the same time the human right to information and protection of life and health are regarded as fundamental human rights. According to the authors it means that carrying out proper Environmental Impact Assessment without Health Impact Assessment is not possible. It would be contrary to the human right to information and the obligation of the authorities to provide citizens with active transparency mentioned by the Inter-American Court of Human Rights and with the principle of fair balance developed in the case-law of the similar European Court together with the objective on sustainable development adopted in Agenda 2030. According to the authors Health Impact Assessment is an immanent and integral part of environmental impact and the possible absence of provisions in the national law requiring investors to carry out HIA where EIA is necessary, does not justify the failure to assess.