In the United States, the Brandenburg test has been applied to the incitement of the illegal action in the physical world. In this paper, the author asks whether this Brandenburg test is applicable in the internet. Cyberspace has several special factors which do not exist in the physical world. Everyone can be the speaker at a cheap price. The message is sent all over the world instantly. This convenient tool has dark sides such as email bombs, and intimidation homepages. In the internet age, we need to ask the question whether the Brandenburg test is modified or abolished totally in this information society because of these special features of the internet. There are various tools to send messages via internet such as e-mail, homepage, blog, newsletter, mailing list, etc. In this paper, the author focuses just on the expression opened to the public. The author believes that before seeing the internet problem, it is necessary for us to see the origin and applicability of the Brandenburg test in the physical world. The Brandenburg test is not a given. Its origin is clear and the present danger test shaped in common law. In the conclusion, the author suggests that the Brandenburg test has some future since it has been used to protect the opinion of the minority in the real world. However, this test was used mostly in the peaceful period. We need to be vigilant to see this test for internet society.