In many cases, what a private person or persons, a group or groups, whether known or not, express on the computer network can be defamating others or regarded as defamation.
The Internet is a useful tool for expressing ourselves. However, the ability to express ideas anytime, anywhere on the Internet creates a risk of defamation by others, and such defamating and illegal acts could easily be expanded and reproduced by copying them. The resulting amount of damage caused can easily become much greater than before the use of the Internet was common in society.
By analyzing decisions of courts of justice on defamation on the computer network, this article examines the responsibility of those who express themselves on the Internet and of the Internet service providers respectively.
It also examines the significance of the Japanese Act on the Limitation of Liability for Damages of Specified Telecommunications Service Providers and the Right to Demand Disclosure of Identification Information of the Senders．