The theory of entrapment

...An investigative method in which an investigative agency or its collaborators (decoys) approach a person who is likely to commit a crime, lead him to commit a crime, and wait for the crime to be committed before catching him. Traditionally, in Japan, following the example of European countries, the only issue that was considered was whether the decoy could be punished as an instigator (the issue of "agent provocateur" ("instigating criminal police")), and it was considered that the perpetrator of the crime could be punished as a matter of course. However, it is inevitable that the state will feel that it is unfair to create a criminal and then catch and punish him, so in America, the punishment of the perpetrator of the crime itself is an issue (theory of entrapment).

*Some of the terminology that refers to the "entrapment theory" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…捜査機関またはその協力者(おとり)が犯罪を犯しそうな者に接近して犯罪に導き，犯罪の実行をまってこれを捕らえる捜査方法。従来，日本では，ヨーロッパ諸国にならって，おとりを教唆犯として罰しうるかという点のみが問題とされ(アジャン･プロボカトゥールagent provocateur(〈教唆する刑事巡査〉)の問題)，犯罪実行者は当然罰しうるとされていた。しかし，国家がみずから犯人を作り出しながらこれを捕らえて罰するというのは不公正の感を免れず，アメリカでは犯罪実行者の処罰自体を問題にする(わな(エントラップメントentrapment)の理論)。…

※「エントラップメントの理論」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報