Kosatsu (street bulletin board in important streets and crossings) (高札)

Kosatsu is the method of public notification by setting up a street bulletin board with written laws and ordinances (general law/the fundamental law) on a board, commonly utilized in Japan since ancient periods until early Meiji Period. Similar bulletin board with written laws and ordinances (special law) issued to a specific person and for particular incident was called Seisatsu but it was difficult to clearly distinguish between Kousatsu and Seisatsu in actual circumstances.

Summary

Although the origin of Kousatsu has not been clearly identified, Daijokanpu (official documents issued by Daijokan, Grand Council of State) issued in 782 describes the order of notifying the contents of kanpu to general public by setting up Kosatsu at government offices or on major streets. Since then, military or feudal governments adapted the same method of public notification. It was Edo bakufu (Japanese feudal government headed by a shogun) and feudal clans which utilized this method as a nation-wide notification system.

The purposes of Kosatsu system were considered to be as follows;
It was to notify the public of new acts and laws;

It was to thoroughly notify the aim of the acts and laws to general public;

It was to make clear that the acts and laws were the fundamental laws; (the violator of the laws were severely punished by death penalty or other severe penalties for his/her 'great crime of the realm')

It was to cultivate the law-abiding spirit of general public to the acts and laws

It was to encourage general public to file a complaint for finding criminals; (as it were, an anonymous tip. High reward was offered for particular complaint, such as to accuse Christian.)

It was to represent the influence and power of Bakufu and daimyo (Japanese feudal lord);

Those can be considered as the reasons.

Most commonly known Kosatsu are 5 boards of Kosatsu published in 1661 ("Erizeni" for eliminating low quality money, "Kirishitan," [Christian] the ban of "Christianity," "Kajiba," the law at the scene of a fire for preventing theft at the scene, "Dachin," the law for money or goods for the purpose of reward and "Zatsuji," the law for personal affairs), 5 boards of Kosatsu published in 1771 ("Chuko," the loyalty and filial piety, "Kirishitan," the ban of Christianity, "Hitsuke," the law at the scene of a fire, "Dachin," the law for money or goods for the purpose of reward and "Dokuyaku, "the law for treating poisons) and 5 posts on the streets released by a new government after the Meiji restoration.

Set up the official Kosatsu site (Seisatsu site) and the use for the education of common people.

Bakufu established a particular site for setting up Kosatsu (Seisatsu) at obvious, noticeable locations for general public, such as the busy corner of the streets, sekisho (checking station), nearby at a large bridge, and at the gates or the center of a town or a village, and Bakufu strictly ordered each domain to follow the method.
Following the Bakufu order, each domain took the similar measure, while Kosatsu was also utilized for the public notification of the act of each domain. (Major examples of the set up location of Kosatsu can be mentioned as follows; Edo Nihonbashi [Chuo Ward, Tokyo Prefecture], Kyoto Sanjo O-hashi Bridge, Osaka Korai-bashi Bridge, Kanazawa Hashiba-cho, Sendai Bashotsuji and so on.)
Kosatsu was also commonly set up at various posting stations, which became the measurement footholds of the distance between each station. For its official nature of the board, it was not allowed to relocate or reprint the written notes (because Kosatsu was written in black ink, it was very weak against winds and rains) without the permission of feudal lord. Instead of requesting the permission for some minor issues, bakufu and domains provided the position called 'Kosatsuban' (the manager of notice boards) to manage the Kosatsu site in full-time base, for repairing or setting up Kosatsu. In order to thoroughly deliver the contents of the notes to the people, the notes of Kosatsu was written in easily understandable mixed writing (characters and kana) or kana sentences, differentiated from the sentence style used for describing general law in code books. Even though bakufu had maintained the policy of prohibiting the publication regarding any general laws, a permission of publishing the act and laws noted on Kosatsu was not only allowed to publish easily in order to thoroughly 'notify those act and laws to all the people', but also the sentences noted on Kosatsu were recommended as textbooks for Terakoya (temple elementary school during the Edo period) to practice dictation skills.

The abolition of Kosatsu and Seisatsu

However, Meiji government decided to discontinue Kosatsu system in 1874, and entire Kosatsu were removed completely from public locations within two years.
The officially announced reason of this decision was that its purpose to notify the general laws to the common people was fulfilled enough, while there was also a background that Western countries expressed objection toward the ban of Christianity in Japan; the actual reasons for the abolition of Kosatsu would have been as follows;

The slow procedure of setting up Kosatsu could not follow the complete changes in the general acts and laws promoted by the Meiji Restoration; (the stationary nature of Kosatsu system for long-term posting of notes in public also did not meet the policy of the new Meiji government who wanted to drastically change and restore the general laws)

It was the economic difficulties that the government of the day could not manage the preservation cost of Kosatsu;

The new methods for thoroughly notifying general laws to the public without depending on Kosatsu system were developed, by newly founded police and judicial systems, educational system, and the popularized mass media such as newspapers;

The inflow of a modern European judicial system promoted the 'unification of the law (legal system),' therefore it was obviously an awkward situation that two variants of a single code co-existed in a government official version and in Kosatsu version for general public;

Those could have been the actual reasons of the discontinuation of Kosatsu system.