Modern studies of mental development suggest that the freedom of developing juveniles is influenced by moral dictates of adults. If adults fail to teach youngsters the accepted rules as they grow so that they do not recognize the value of law, they are likely to diverge from accepted behavior. Mentally retarded individuals, psychotics, and neurotics can become criminal because they cannot identify the limitations of their freedom. In these cases, as in the previous one, society must intervene to prevent crime. Obviously, the conceptions of crime and liberty depend on the norms of the culture involved. The abstract notion of liberty which determines the necessary barriers for individuals who commit acts not in conformance with norms is also affected by changes in social conditions over a period of time. Measures to encourage mental health are thus necessary to assure normal development of individuals' relationships to their society. Such measures include removal of factors detrimental to mental health and safety, education of parents, and modification of neurotic behavior. The whole society must participate in these efforts. Awareness of the difference between individual definitions of liberty and liberty as established by the wisdom of an adult society presumes recognition of the role of individual personalities in criminal behavior. Notes are supplied. --in French.