How might overcrowding hinder correctional treatment?The problems can be categorized into the following three points.

  First,deterioration of inmates'living environment is a problem.An overcrowded environment causes tension and pressure among inmates,which may negatively influence their mental state and obstruct provision of correctional treatment for their reform and reintegration into society.

  Second,overcrowding causes various problems for the management of penal institutions.
  Penal institutions need to leave some cells unoccupied for separation of troublesome inmates,for protection of inmates who are endangered by bullying or for isolation of undisciplined inmates.Even prior to the assignment of the cell and work at factory,inmates'individual characteristics are under consideration to avoid unnecessary conflicts as mentioned above.Thus,even if particular positions are available,that does not mean all inmates can be allocated to them.Furthermore,some cells may not be available due to repair work,etc.
  Therefore,penal institutions need a certain amount of capacity leeway to ensure smooth management and they should be operating below their capacity.
  Stress caused by an overcrowded environment can trigger troubles among inmates and violence against institution officers. Fig. 5-3-1-5 shows the trends in the occupancy rate of capacity for convicted prisoners over the past20years,the total number of persons on which disciplinary punishment was imposed and the number of persons on which disciplinary punishment was imposed for homicide,injury or assault(including those among inmates and against institution officers). Fig. 5-3-1-6 shows the trends in the occupancy rate of capacity for convicted prisoners and the rate of homicide,injury,and assault(the number of persons on which disciplinary punishment was imposed per1,000convicted prisoners).
  These figures show that the number of persons on which disciplinary punishment was imposed is clearly correlated with the occupancy rate of capacity.In particular,the trend of the rate of homicide,injury and assault shows a similar curve to the occupancy rate of capacity.This indicates that an overpopulated environment is likely to cause stress among inmates and generate managerial problems.

Fig. 5-3-1-5Trends in the occupancy rate of capacity and persons on which disciplinary punishment was imposed(1984-2003)

Fig. 5-3-1-6Trends in the occupancy rate of capacity and rate of homicide,injury,and assault(1984-2003)

  Third,overcrowding may obstruct inmates'reform and reintegration into society,which is the very purpose of correctional treatment.
  Under the Japanese correctional system of classified treatment,inmates are classified depending on their individual characteristics and treated differently according to their classification.This system operates on the premise of prompt transfer and accommodation of inmates into the most appropriate institutions.However,the present overcrowding situation makes it difficult to find the appropriate institution for each inmate and their waiting periods at detention houses for next available penal institutions have been getting longer and causing delays in implementation of full-fledged treatment in some cases.
  As the inmate population increases,allocation of appropriate prison work to each inmate or application of progressive treatment programs according to their conduct are also difficult to administer.As of the end of May,2004,about10%of774Progressive Grade1inmates(excluding those under pre-release guidance)and about50%of13,259Progressive Grade2inmates(excluding those under pre-release guidance)were accommodated with inmates who are classified as other grades(Source:Data by Correction Bureau,Ministry of Justice).
  Furthermore,due to the shortage of classrooms and institution officers in charge of educational treatment or restrictions on the capacity of class enrollment,inmates are kept waiting to participate in anti-stimulant abuse programs or other guidance by classification group.Even in the case inmates were able to participate,the length of those courses may be shortened.

  As mentioned above,the overcrowded prison situation has caused noticeable problems regarding(1)inmates'living environment,(2)institutional management and(3)application of appropriate correctional treatment.It is clear that securing enough imprisonment capacity and space to meet the actual numbers of convicted offenders are vital to fulfill the demands from all three aspects.