An investigation should be conducted on new prisoners for an understanding of their personality , physical and mental conditions, past experiences, curriculum vitae, educational attainment, and other personal matters.
The foregoing investigation procedure shall take less than two months.

The personality and the physical and mental conditions of prisoners should be assessed pursuant to professional medical, psychological, educational, and sociological evaluation standards.

In response to the investigation requirements, an application for perusing the case litigation transcripts of a prisoner may be filed with the court, and reports may be requested from autonomous organizations, police authorities, schools and other parties to which the prisoner is related or under which the prisoner has been employed or placed in protective custody.

All matters under investigation shall be recorded in the investigation form.

In order to prevent the escape, suicide attempts, violent behaviors, or other disciplinary violations of prisoners during their respective investigation periods, proper administration procedures should be implemented providing such do not obstruct the character investigation process.

During the period of investigation, it is imperative to pay close attention to the language and behavior of the person(s) having contacts with prisoners. Discovery of any language or behavior affecting the personality or physical and mental conditions of prisoners should be reported immediately to the executive personnel.

Prisoners under investigation should engage in work suitable to their conditions; during which, their stamina, patience, industry, skills, and efficiency should be assessed to enable determination of a suitable work assignment.

Upon conclusion of a particular case investigation, the warden should immediately decide whether progressive treatment regulations are applicable to the particular prisoner. If so, the prisoner concerned should be duly notified of the purpose of the progressive treatment. If progressive treatment is not applicable, a pertinent report should be made to the Prison Affairs Committee.

Prisoners subject to progressive treatment shall be classified into first offenders, second offenders, and recidivists, and further sub-classified according to their ages, criminal convictions, sentence terms, and other information obtained during the investigation for proper treatment.
The procedures for prisoner investigation and classification are subject to the discretion of the Ministry of Justice.

Level 1 and Level 2 prisoners are not subject to the classification defined in the preceding article.