Individuals With Impaired Decision-Making Capacity are those persons having a psychiatric or developmental disorder that affects cognitive or emotional functions to the extent that the capacity for judgment and reason is significantly diminished. Other persons, including those under the influence of or dependent on alcohol or drugs, those affected by degenerative brain diseases, those who are terminally ill, and those who have severe physically disabling handicaps, may be compromised in their ability to make decisions in their best interests. Individuals with impaired decision-making capacity may not be able to give legally valid informed consent. However, researchers have a responsibility to persons with cognitive impairments (1) to inform subjects with impairments about the procedures, risks, and benefits of the research to the extent that the subject can understand, and (2) to obtain affirmative assent in so far as the subject is able to do so.

Selection of subjects is a particularly important issue as it relates to persons with cognitive or emotional impairments. Research involving persons whose autonomy is compromised by disability or restraints on personal freedom should bear some direct relationship to their condition or circumstances. Persons who are institutionalized should not be chosen as subjects simply because it is convenient to the researcher. Nevertheless, persons do not become incompetent the moment they enter a mental institution, and their right and considered judgment to participate in research should be respected.