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In 1889, Japan became the first East Asian nation to adopt a written constitution. Japan has a civil law system. In the last half century, it has implemented significant judicial and legal reforms, including the introduction of lay participation in criminal cases.

Six koi fish representing the six codes governing Japan

The Six Codes

Japan’s legal system is based on the roppō (“Six Codes”):

The Constitution of Japan
The Civil Code • The Code of Civil Procedure
The Criminal Code • The Code of Criminal Procedure
The Commercial Code

Gen. Douglas MacArthur and Emperor Hirohito of Japan from manhhai on Flicker, edited by Celine Calpo

Western Influence

After World War II, the United States occupied Japan and oversaw wide-ranging reforms across society and government. The immediate postwar era prioritized disarmament, democracy building, and international reintegration. The Japanese constitution and legal system were consequently envisioned. Japan’s new constitution assigned the emperor a more symbolic role and included a “Pacifist Clause” eliminating the government’s power to declare war. U.S. influence on legal reforms included the introduction of adversarial-style court procedures and increased rights for the accused in criminal cases.

Court System

There are five types of courts in Japan:

Summary Courts

Summary courts handle civil lawsuits involving claims up to 1.4 million yen, small claims, and civil mediation, as well as minor criminal cases and those designated by statute (e.g., theft and embezzlement).

Family Courts

Family courts have jurisdiction over domestic relations and juvenile cases, including family conciliation, personal status, and adoption.

District Courts

District courts are the courts of first instance for civil, administrative, and criminal cases—except those specifically assigned to other courts. They have appellate jurisdiction over first-instance judgments in civil cases from the summary courts. A single judge presides over most cases; a three-judge panel hears appeals from the summary courts, more serious criminal cases, and other select cases.

High Courts

High Courts hear appeals from the lower courts (i.e., district, family, and summary courts), unless a statute designates otherwise. Criminal verdicts are appealed directly to a high court; civil judgements from summary courts are heard by the district court before appeal to a high court. High Courts also have jurisdiction over cases involving elections, criminal insurrection, and decisions issued by quasi-judicial agencies. Japan’s Intellectual Property High Court has exclusive jurisdiction over patent cases and appeals from the Japanese Patent Office. High Court judges usually sit in three-judge panels; five-judge panels are reserved for cases involving insurrection, disciplinary cases, and some patent cases.

The Supreme Court

The Supreme Court is the highest court in Japan, hearing final appeals from the High, District, Family, and Summary Courts and correcting erroneous interpretations of the constitution. The Supreme Court has limited original jurisdiction. There are fifteen justices on the court. Five-justice panels, each called a “petty bench,” are assigned to civil, criminal, or administrative cases. The “Grand Bench,” with all fifteen justices, hears the cases involving constitutional interpretation as well as referrals from a petty bench when there have been conflicting petty bench rulings.

Infographic showing the composition of a petty bench (5 justices) and grand bench (15 justices)

Nine-Judge panel Saiban-In illustration
Four-Judge panel Saiban-In illustration
Saiban-In Seido (“Lay Judge System”)

The first recorded Japanese account of trial-by-jury dates to 1873, when Meiji historian Kunitake Kume published his observations of a jury trial in Paris. Kume’s description generated much interest, leading to the judiciary’s experimentation with different lay participation systems. In 2009, Japan implemented saiban-in seido for serious criminal cases. Under the saiban-in system, citizens sit with professional judges to hear evidence, deliberate, and impose sentences. Citizens are selected for saiban-in service through a voter registration roll lottery. Most saiban-in trials have a three-judge panel and six lay judges; in trials with a single presiding judge, there are four lay assessors. Advocates of saiban-in believe that it contributes to democratic engagement, civic education, and increased trust in the criminal justice system.

Legal Education

In the early 2000s, Japan realized that more attorneys were needed to support the growing regulatory state and increased transnational business. The Justice System Reform Council of Japan published a set of recommendations to modernize legal education. Prior to the reform, the study of law was a four-year undergraduate degree designed to provide a “general education with a major in law.” Students interested in entering the legal profession took a bar exam; the low pass rate for the exam, 1% to 3%, led to the shortage of lawyers.

The Council introduced graduate legal education, following the American “law school” model, and a new national bar exam. Graduates who pass the bar exam enroll in an apprenticeship program through the Legal Training and Research Institute of Japan (LTRI). The Institute provides training and has a research office. LTRI graduates are eligible to become assistant judges, public prosecutors, or practicing attorneys. Because Japanese judges often begin their careers directly after their apprenticeships, they tend to be younger than their counterparts in other countries.

Judicial Selection, Tenure, and Appointment

The emperor exercises ceremonial authority over the judicial appointment process. Japan’s Cabinet, the top executive body, has actual authority. The Chief Justice of the Supreme Court is appointed by the emperor based upon the Cabinet’s nomination; associate justices are appointed by the Cabinet with the emperor’s approval. Members of the supreme court are drawn from the lower courts, prosecution service, bar, and legal academia. Justices are subject to retention elections every ten years until they reach the mandatory retirement age of seventy.

Lower court judges are appointed by the Cabinet from a list of nominees prepared by the Supreme Court and reviewed by a special advisory committee on nominations. They usually begin their career as assistant judges, meaning that they serve as part of a collegiate body for at least five years until nominated by the Supreme Court to hear cases alone. Lower court judges serve renewable ten-year terms with a mandatory retirement age of sixty-five. Summary court judges also serve renewable ten-year terms, with a mandatory retirement age of seventy.

Career judges are assigned to a multitude of posts, typically for three-year periods. Newer assistant judges traditionally start in Tokyo, Osaka, or another large metropolitan area. Judges are assigned throughout the country during their three-year periods but eventually are assigned to a single region for the remainder of their career. Routine judicial rotation not only offers a geographically diverse experience for judges but also provides an opportunity to serve in different types of courts. The rotation period may include assignment to the Supreme Court as a research or administrative assistant; this post is often followed by service as a senior or presiding judge of a lower court.

Sample rotation of a Japanese Judge