Unable to regain the necessary social skills for leading a ‘normal’ life, some may continue to live in relative social isolation after their release. In this sense, solitary confinement operates against one of the main purposes of the prison which is to rehabilitate offenders and facilitate their reintegration into society. 2.7 Concluding remarks about the effects of solitary confinement There are problems in drawing general conclusions from studies of particular prisoners and from experimental research with volunteers. Studies carried out with prisoners in the context of lawsuits being brought by the prisoner against the authorities raise questions about the partiality of the findings, as do studies carried out by medical professionals employed by the authorities responsible for the confinement. Getting access to prisoners in real life segregation for research purposes raises both practical difficulties and ethical concerns. There is also a clear lack of equivalence between the experience of solitary confinement in real life prisons and within the context of time-bounded experiments. The role of pre-existing mental health problems is also a significant compounding variable. Nevertheless, there is a large and growing body of literature that demonstrates the harmful impact of isolation, particularly when used punitively, without clear time limits, for periods that are longer than four weeks and for people with prior mental health problems and poor social adjustment. Key points • There is unequivocal evidence, dating back to the 19 th century, demonstrating the negative health effects of solitary confinement. • The extent of psychological and physiological damage of solitary confinement will depend on the individual prisoner, his background, the context of placement in isolation, its duration, conditions of confinement and degree of mitigation. • Uncertainty about the expected duration of solitary confinement is likely to increase its adverse effects. • While some of the health effects of solitary confinement will subside upon its termination, others may persist. • For these reasons, the use of solitary confinement should be reserved for extreme cases, for as short time as possible, but usually no more than a matter of days. • The misuse of the psychological and physiological effects of solitary confinement as part of an interrogation process may amount to cruel, inhuman or degrading treatment or punishment and even to torture, and should be prohibited in all circumstances. Sourcebook on solitary confinement: The health effects of solitary confinement 23