Agreement from a potential participant that he or she is willing to take part in a clinical study and is aware of what the study involves.

The principle of informed consent ensures that participants willingly take part in clinical studies and are fully aware of what the studies involve. To give informed consent, a potential participant must have received sufficient information in a format that enables them to understand the implications of their decision, and they must have sufficient reasoning powers to interpret the information provided.

Special procedures are applied for those unable to give informed consent, for example, because of age, a decline in cognitive abilities or severe illness.