Because of concerns about competence and voluntariness, the mentally d
isordered constitute a vulnerable population in the context of nonther
apeutic biomedical research and, as such, are in need of protection. D
espite others' concern about protecting the mentally disordered, their
decision-making potential should also be respected and maximized, all
owing such individuals to consent to participate in experiments subjec
t to an evaluation of their competence to make such a decision. Compet
ent mentally disordered persons who anticipate future incapacity shoul
d be able to issue research directives or durable powers of attorney w
hereby they can provide explicit consent to participate in nontherapeu
tic research. When he or she becomes incompetent, a substitute decisio
n maker should be able to provide consent on behalf of the mentally di
sordered person within established parameters. Nontherapeutic experime
ntation with the mentally disordered should be permitted, but only wit
hin the boundaries of ethical permissibility delineated by legislated
guidelines. At present, the legal status of substituted consent for no
ntherapeutic procedures is uncertain and requires legislation, which i
n addition to legalizing such consent would provide guidelines for sub
stitute decision makers and for the creation of research directives. T
hese guidelines should include restrictions on the scope of research,
obligations of researchers, rights of subjects, and responsibilities o
f research ethics committees (RECs). In all cases, the voluntary and i
nformed consent of the person or substitute decision maker must be obt
ained.