The penal system was administered by the Department of Corrections within the Ministry of Interior. The government's stated policy in operating the system was to use its facilities to reduce crime by correcting and rehabilitating offenders rather than only punishing them. Rehabilitation of convicted offenders was a relatively recent penal concept in Thailand, however, and proper facilities, programs, and specially trained penal staff were limited.

In the late 1980s, the system consisted of forty-six regular penal institutions, including seven central prisons, five regional prisons, twenty-three prison camps, seven correctional institutions, three reformatories, and one detention home. In addition, all metropolitan, provincial, and district police stations had jails of varying adequacy for offenders whose sentences did not exceed one year.

The seven central and five regional prisons housed the majority of prisoners with long-term sentences. Khlong Prem Central Prison in Bangkok, with a capacity of 6,000 inmates, was one of the oldest and largest. A maximum security institution for habitual criminals was operated at Nakhon Pathom. Twenty-three prison camps were located on Ko Tarutao, an island in the Strait of Malacca. The camps accommodated an average of fifty good-conduct prisoners, who worked principally in agriculture, preparing themselves for employment after their release.

Two correctional institutions, one at Ayutthaya and one in Bangkok, held primarily offenders eighteen to twenty-five years old serving terms of up to five years. The Women's Correctional Institution was also located in Bangkok, and the specialized Medical Correctional Institution for drug addicts and other prisoners who required medical attention was located in Pathum Thani Province north of the capital. Minimum security correctional centers were located at Rayong and Phitsanulok.

Of the three reformatories, the Ban Lat Yao facility, just north of Bangkok, with a capacity of about 2,000, received the majority of the more recalcitrant juvenile delinquents. Limited rehabilitation activities were undertaken there those who failed to respond were sent to a second reformatory near Rayong, which was operated on the prison farm principle. A third reformatory at Prachuap Khiri Khan, about 200 kilometers southwest of Bangkok, was used only to accommodate the overflow from the other two institutions.

Additional special facilities for juvenile offenders, called observation and protection centers, were administered by the Central Juvenile Court and the Central Observation and Protection Center of the Ministry of Justice. Attached to each juvenile court, the centers assisted in caring for and supervising delinquent children charged with criminal offenses, both before and after trial. Probation officers, social workers, and teachers assigned to the centers aided the court by collecting information on the background and home environment of offenders, by taking them into custody pending trial, by accompanying the defendants into court, and by reporting to the court on their mental and physical conditions. 358 .

Health conditions in all types of penal institutions improved during the 1970s and 1980s, but more hospital facilities were needed. Prison education facilities conducted literacy classes for 20,000 prisoners each year. Vocational training workshops also were established in some prisons. Products from prison labor were sold, and 35 percent of the net profit was returned to the prisoners. Some of this income could be spent during incarceration, but most of it went into a savings fund to assist the prisoner in making a new start after release.

Data as of September 1987