1. Formal issues (ethical approval obtained, inclusion of participants in accordance with national law and relevant ethical guidelines, etc.)
2. Respect for autonomy and privacy: participation informed and voluntary or not?
3. Harm or risk of harm to the concerned individuals or to some group(s) the individuals belongs to. For instance, research on an already stigmatized group may, in some circumstances, if carried out in certain ways and producing certain results, increase stigmatization. There may, in principle, be psychological and social effects of bringing up the past, depending on what is researched, what the results are and how they are communicated.