There is almost a universal agreement that informed consent is of the most important ethical principle in research ethics. By way of informed consent, the prospective research participant comes to an understanding of the goals of a research and of what participation in it would involve so that he/she can make his or her own free decision about whether, and under what conditions, to participate. In order for informed consent to be considered valid it must meet at least the following three criteria:

• Adequate information (i.e., what a reasonable person would need/want to know, such as, among other things, the purpose of the research or any potential risks involved in order to decide whether or not to take part in the proposed research),
• Voluntariness (i.e., the consent must not result from coercion, manipulation, or undue inducements),
• Competence (i.e., having enough mental capacity to understand and retain relevant information about the research as well as to communicate his/her views on the research).