The public prosecutors and police officers take charge of investigation of crimes. As a general rule, a suspect is put under investigation without being arrested or detained. However, under certain circumstances, the investigative authorities can arrest or detain a suspect after they obtain a warrant from a judge. If a suspect is caught in the act of committing a crime or exigent circumstances exist, a warrant may be obtained after arrest. A judge issues a warrant only if a suspect has no fixed dwelling or there are reasonable grounds to believe that a suspect may attempt to escape or to destroy evidence.

Criminal proceedings begin with the indictment of a public prosecutor unless otherwise provided by law. The public prosecutor may bring a case before the court by summary proceedings when it is deemed that the offense is punishable by fine. In such a case, the judge usually issues the summary order without holding a trial. If the judge deems it inappropriate to issue the summary order, he/she can refer the case to regular trial proceedings. The accused may also request regular trial proceedings within seven days from the date of the notification of the summary order

The hearing is held at the courtroom on the hearing date and is open to the public. It starts with the presiding judge asking the accused personal identification such as name and date of birth. Then follow a statement by the public prosecutor of the essentials of the accusation, direct questioning of the accused by the public prosecutor, cross-examination of the accused by the defense counsel, examination of evidence, statement of opinion by the public prosecutor, closing argument by defense counsel, and final statement by the accused.

After the conclusion of the aforementioned, the court closes the hearing and renders a judgment.

The accused is entitled to receive the assistance of counsel for his/her defense in the course of investigation as well as trial proceedings. Trial proceedings cannot proceed in the absence of defense counsel when the accused is charged with an offense punishable by death penalty, life imprisonment, or imprisonment for a minimum of three years. In such a case, if no defense counsel has been appointed by the accused, the court should assign a defense counsel ex officio.

Moreover, the court should also assign a defense counsel ex officio in the following circumstances: where the accused is a minor; where the accused is 70 years of age or over; where the accused is deaf-and-dumb; where the accused is suspected of mental and physical unsoundness; and where there is a request by an indigent defendant. The defense counsel assigned by the court is called assigned counsel or public defender.

In the event that the investigative authorities, after arrest of the suspect, seek a warrant of detention, the suspect, his/her defense counsel, legal representative, spouse, lineal relative, brother or sister, head of household, member of family, cohabitant, or employer may request the judge to examine the suspect before deciding on whether to issue a warrant of detention. The public prosecutor or police officer should inform the suspect of the right to request examination and indicate on the record whether the suspect has requested examination or not.

When the investigative authorities seek a warrant of detention for a suspect who is not under arrest, the judge, if it is deemed necessary, may examine him/her ex officio before deciding on whether to issue a warrant of detention.

Examination of the suspect is presided over by a judge. The suspect and his/her defense counsel are granted the opportunity to fully state the opinion concerning the offense he/she is suspected of and the grounds for detention. Taking into account the result of examination as well as the records submitted by the investigative authorities, the judge decides on whether the grounds for detention exist and whether the circumstances justify the detention.

The suspect or any of the concerned persons mentioned above may request the competent court to review the legality of arrest or detention before the public prosecutor institutes a criminal action, when the warrant of arrest or detention has been issued against law or when circumstances have substantially changed after the detention. The court, promptly reviewing the legality of arrest or detention, orders the release of the accused where there is a valid ground for the request.

The court may permit release of the accused upon request by the accused or ex officio under the condition of payment of bail money aka release on bail. A written undertaking accompanied by a surety insurance policy may be substituted for bail money. When release on bail is granted, the court usually orders the defendant to remain within the physical boundaries of his/her immediate neighborhood or home.

In criminal proceedings, it lies upon the public prosecutor to prove guilt of the accused. The court determines guilt or innocence of the accused on the basis of evidence produced by the public prosecutor and in conformity with the Constitution and law. When a confession by the accused is the only evidence against him/her, he/she cannot be judged guilty. Corroborating evidence in support of a confession is indispensable for conviction. Confession of the accused extracted by torture, violence, threat or after unjustly prolonged detention, or suspected to have been made involuntarily, can not be admitted as evidence of guilt.

The accused has the right to remain silent and may refuse to answer any of the questions.

If guilt has not been proved beyond a reasonable doubt, the court declares the accused not guilty. In such a case, the accused who has been placed under detention is entitled to claim compensation as provided by law. The court finds the accused guilty if the charge against the accused constitutes a crime and evidence is sufficient for conviction. Once the accused is found guilty, the court imposes punishment such as the death penalty, imprisonment with labor, imprisonment without labor, deprivation of qualifications, suspension of qualifications, fine, penal detention, minor fine, and confiscation. Imprisonment with or without labor can be either for life or for a specified term. The specified term is usually from one month to 30 years, but it may be extended to 50 years in light of certain aggravating circumstances.

Not only the accused but also the public prosecutor can bring an appeal against the judgment rendered by the trial court within seven days from the date the judgment is rendered. There is little difference between the appeal and trial proceedings. In case an appeal has been lodged by the accused, the punishment cannot be severer than the original judgment. Appeals against the judgment of court of appeals may be filed with the Supreme Court within seven days from the date the judgment is rendered. Appeal to the Supreme Court must contain one or more of the grounds specifically prescribed in the Criminal Procedure Act.

A judge of a district court, a branch court, or a municipal court may impose a fine not exceeding 200,000 Korean won (approximately US$ 177 as of October 2015) or penal detention for less than 30 days under summary trial proceedings in misdemeanor cases such as violation of Road Traffic Act, a Punishment of Minor Offenses Act, etc. The chief of the competent police station, not a public prosecutor, is entitled to bring a case before the judge under summary trial proceedings.

If a judge deems that a case is inadequate for summary trial proceedings, the judge is to dismiss the case. After the dismissal, the chief of the police station needs to take the case to the District Public Prosecutor's Office without delay.

Either the accused or the chief of a police station, if dissatisfied with the judgment, may apply for regular trial proceedings within seven days from the date the judgment is rendered. When a judgment under summary trial proceedings becomes final and conclusive, it has the same effect as a final and conclusive judgment under regular trial proceedings.