If any evidence necessary for the investigation of a criminal case in Japan exists in a foreign country, Japan requests assistance in investigation by means of comity of nations through diplomatic channels, in principle. Either the public prosecutors office or the police etc. may make such a request, which shall be sent to the foreign country concerned via the Ministry of Foreign Affairs of Japan. If Japan is requested by a foreign country to provide evidence necessary for the investigation of a criminal case, Japan can provide assistance in investigation in accordance with the requirements and procedures provided in the Act for International Assistance in Investigation etc. (Act No. 69 of 1980) under the guarantee of reciprocity, even to foreign countries that have not concluded treaties on assistance with Japan.
  For the purpose of further strengthening cooperation for assistance in investigation, Japan signed the Treaty between Japan and the United States of America on Mutual Legal Assistance in Criminal Matters (hereinafter referred to as the "Japan-U.S. Mutual Legal Assistance Treaty") in August 2003. The conclusion of the treaty was approved by the Diet in May 2004, and the treaty took effect in July 2006, following the exchange of instruments of ratification in June 2006. Japan also signed the Treaty between Japan and South Korea on Mutual Legal Assistance in Criminal Matters (hereinafter referred to as the "Japan-Korea Mutual Legal Assistance Treaty") in January 2006, and the conclusion of the treaty was approved by the Diet in May 2006. At present, negotiations for concluding similar treaties have been underway with China and Russia.
  Under the Japan-U.S. Mutual Legal Assistance Treaty and the Japan-Korea Mutual Legal Assistance Treaty, the Minister of Justice, the National Public Safety Commission, or persons predetermined respectively by them are required to be designated as the "central authorities" to send or receive requests for assistance. After the treaty comes into effect, the Ministry of Justice or the National Police Agency of Japan will be able to send requests for assistance directly to the judicial authorities of the U.S. or South Korea without using diplomatic channels. At the same time, the judicial authorities of the U.S. and South Korea will be able to send requests for assistance directly to the Ministry of Justice of Japan.
  Table 2-6-3-1 shows the trend of requests for mutual legal assistance in investigation between Japan and foreign countries over the last five years.

Table 2-6-3-1  Requests for mutual legal assistance in investigation (2001-2005)