For example, consider a study in which researchers propose to assign
individuals randomly to an experimental HIV vaccine or a placebo. The
principle of autonomy suggests that, as long as the individuals are adequately
informed of the risks and benefits, they should be free to decide
for themselves whether to participate or not. However, the principle of
beneficence might lead a research ethics committee to require that the
researchers offer participants counselling about risk-reduction methods
and possibly care for individuals who become infected during the
study. Based on the principle of nonmaleficence, the committee would
have to consider whether participating in the study might harm individuals
by leading them to think that they are protected from infection
and therefore do not need to use risk-reduction measures. Finally, the
principle of justice would require consideration whether the burdens
of the study fall disproportionately on particular populations.