People in extraordinary situations are vulnerable. As research participants, they are additionally threatened by abuse or exploitation and the possibility of harm through research. To protect people against these threats, informed consent as an instrument of self-determination has been introduced. Self-determination requires autonomous persons, who voluntarily make decisions based on their values and morals. However, in nursing research, this requirement cannot always be met. Advanced age, chronic illness, co-morbidity and frailty are reasons for dependencies. These in turn lead to limited abilities or opportunities for decision-making and self-determination. Exclusion of vulnerable people from research projects would disadvantage them by not covering their needs, which would violate the ethical principles of justice and beneficence. Commonly, vulnerability is attributed to social groups. The consequence for individuals, attributed as belonging to such a vulnerable group, is that the principles of respect for autonomy, justice and beneficence are subordinated to the principle of non-maleficence, understood as avoiding the risk to cause more harm than good. In addition, group-specific attribution could lead to stigmatizing because labelling a person as deviation from a norm violates integrity. For clinical nursing research, the question arises how the protection of vulnerable people could be granted without compromising ethical principles. The concept of relational ethics provides a possible approach. It defines vulnerability as the relation between a person’s health status and the extent to which this person is dependent on the researcher and the research context. Vulnerability is not attributed solely to a person but to a situation, meaning the person is viewed in context. By combining vulnerability as a context-related and situational concept with existing approaches of informed consent, the different ethical principles can be balanced and preserved at every step of the research process.