Japanese System of International Law

This is a note prepared for an international conference held by Keio University, Tokyo, and Donan University, Nanjing, in the summer of 2000, when the author was an undergraduate student. Note that it was neither reviewed by professional peers or corrected for grammatical errors; do not quote it.


There are various political systems of states in the world; presidential governmments, parliamentary governments, absolute monarchies, constitutional monarchies, and hybrid systems of these ones. Similarly, there are various systems of international law. Each state has in each domestic law a rule which provides the way to conclude international treaties and the way to execute the contents of the treaties. It can be said that there may be as many systems of international law as states.

The following texts deals with the system of international law, especially the system of international treaties of Japan. First comes explanation of the system of orthodox treaties: treaties which are concluded through the process determined by the Constitution, and have perfect validity in international- or domestic relations. Second, defective treaties are dealt with. When a treaty lacks legistimacy in its content or process of conclusion, it is called a defective treaty. Theories and precedents have told what international- or domestic validity should be permitted to a defective treaty.

Orthodox Treaties

Well then, let's start with the system of international law which is prescribed in the Constitution of Japan.

How a treaty is concluded

The Constitution of Japan adopts the system of separation of the three branches of government, following many other democratic states. The power of legislation is entrusted to the Diet, judiciary to the Court, and administration to the Cabinet. These three are independent of one another, and watch each to keep one of them from abusingr its privaledge.

Of these three, the Cabinet is empowered to conclude international treaties with other states. Practically, an ambassador plenipotentiary entrusted by the Cabinet signs international convention, then the Cabinet ratifies it.

The Cabinet, however, needs consent of the Diet in advance or after the fact to conclude a treaty. This system has following background;

An international treaty has domestic/internal effect as well as international/external one. The nation of Japan may be imposed obligations by an international treaty concluded by the Japanes Cabinet. That is, conclusion of a treaty is a legislative action. The Constitution of Japan article 41prescribes that "the Diet shall be the highest organ of state power, and shall be the sole law-making organ of the State." Essentially the Diet should be enpowered the right to conclude treaties. However, the Diet is not good at flexible and speedy diplomacy. That is why the system of Cabinet conclusion and Diet consent is adopted.

At the last of the process, the Emperor promulgates the treaty. The Constitution of Japan article 7 prescribes that the Emperor shall perform "promulgation of amendments of the constitution, laws, cabinet orders and treaties" and "attestation of instruments of ratification and other diplomatic documents as provided for by law" with the advice and approval of the Cabinet on behalf of the people. This promulgation means just a public declaration and is not a necessary requirement.

Conversion of a treaty into domestic law

Signatory of a treaty has obligation to observe and execute the convention. Viena Convention on the Law of Treaties article 26 prescribes:

It is entrusted to the domeatic law of each state what legal status and effect shall be given to a treaty in a nation.

Attitudes of states can mainly be classified into to types:

1st, some states think that a treaty itself has no legal states or effect in the domestic law system. In these states, execution of a treaty needs definit legislation for it. United Kingdom of Great Britain and Northern Ireland, and many other Common-Wealth countries adopt this system.

2nd, other states assume that a concluded treaty has naturally domestic validity in the law system of signatory. For instance, Argentine Republic, Republic of Austria, and Grand Duchy of Luxemburg follow this principle.

Japan belongs to the latter group. Although the constitute of Japan gives no definite account of this matter, article 98 clause 2 sais that "the treaties concluded by Japan and established laws of nations shall be faithfully observed", and theories in Japan have interpreted this provision as such.

Practical buisiness affairs of japanese courts also support that interpretation. Decision by the High Court of Tokyo on 28th February 1953 said;

Treaties bind states as rules of international relationships. Treaties of which contents include domestic legislative elements shall be given domestic effects and bind the people of signatory immediately after their promulgation

Treaties with Defects

Next, we are going to deal with Defective Treaties, which are treaties with some imperfect points in contents or process of conclusion. For example, a treaty of which content conflicts with domestic law of the signatory is defective.

International validity of a defective treaty

An international treaty has two sides of its effect; international- and domestic one. A treaty is always internationally effective, even if it has defects in its contents or process of conclusion. One signatory of the treaty must assume responsibility to the other signatory to fulfill the content of the convention.

This principle has been supported by customary international law for a long time. On 4th February 1932 the Permanent Court of International Justice defined its opinion on this issue:

It is a generally approved principle that a state can assert only international law and international obligation against other states. Asserting a domestic law or constitution to avoid responsibility based on international law or treaties is not permitted.

Permanent Court of International Justice and, after the World War 2, International Court of Justice have refered this principle in the decisions over and over. And today, the Viena Convention on the Law of Treaties article 27 and article 46 stipulate the principle.

Domestic validity of a defective treaty

There is no difinite provision on the domestic effect of a defective treaty in the Constitution of Japan. Article 98 clause 1 says;

This Constitution shall be the supreme law of the nation and no law, ordinance, imperial rescript or other act of government, or part thereof, contrary to the provisions hereof, shall have legal force or validity.

This text gives no indication about the domestic validity of a defective validity. If a treaty concluded by the government conflicts the Constitution of Japan, what domestic effect should be endorsed? About this issue, three types of theories have been advocated;

Common opinion among scholars of the Constitution have adopted the 2nd type theory. However, the practical business afairs of the courts of Japan have been a little different from that.

The decision of the high court of Tokyo on 2nd April 1966 mentioned the superiority of international treaties to domestic ordinal laws, and judged that if a treaty had confliction with an ordinal law in their contents the former should be given priority over the latter. In the system of domestic law of Japan, the effect of ordinal laws is superior to that of budget and inferior to that of constitution. Therefore international treaty, which has speriority to ordinal law, is naturallly superior to budget.

Then, what relationship shall be between constitution and international treaties? The supreme court of Japan refered about this issue in a decision on 16th December 1959. In that text, the supreme court judged that even international treaties might be domestically invalid for the unconstitutionality, though treaties with highly political character should hardly be the target of inspection. This view of the court has been criticized by a lot of scholars for its noncomittalness. However, it also has been supported by many judicail precedents, and is a dominant opinion today.

To bring the matter to a settlement, in the law system of Japan the domestic effect of an international treaty is greater than that of an ordinal law, and less than that of the Constitution. If a treaty which conflicts with the Constitution of Japan concluded, the treaty shall have domestically no legal validity though international obligation to execute the convention cannot be denied. If a treaty which conflicts with an ordinal law, the former shall be internationally and domestically valid and the latter shall be neutralized or paralysed its effect as long as it has confliction with the treaty.

For Afterwords

Lack of stipulation

The Constitution of Japan lacks precise stipulations on the system of international law, especially on how to deal with defective treaties. The article 98 clause 1and 2 are equivocal. Why is the Constituion taciturn about this issue?

The Diet at the time when the Constitution was established expressed that concrete stipulations about international law were intentionally left out. Establishers of the constitution found it beneficial to entrust contemporary theories and practices with interpretation of flexible texts rather than to decide precise provisions.

Interpreter's Responsibility

Although this idea may sound irresiponsible, it has considerable rationality. Amendments of the Constitution of Japan requires very strict condition. In fact, the Constitution has never amended from the day of its birth. However, the government needs flexible management of the Constitution to keep up with the international situation of the time. Too precise provisions of Constitution might be hindrance to the diplomacy of Japan.

Thus, theories and interpretations have essentially built up the system of international law of Japan. We, international law students, must study it from a viewpoint of contemporary trend of theories and practices as well as statutory law.

HIRANO, Takashi