The United States copyright law

After that copyright law were repeatedly change to adapt to the emergence of new technologies such as recording, and to extend the protect time, there are also some other change.The court's understanding of section 8 of the constitution is the purpose of copyright is encouraged to create better works for public, so if the conflict between public interests and the interests of the writer, the public interests than the writer's position High.This understanding methods lead to the rational use of the law.Some of the copyright owner tried to expand the application scope of copyright law, as their led to the abuse of the copyright.    

The United States copyright law to distinguish between "idea" and "practice" of these two basic concepts, but the distinction between these two concepts is not very clear.A description of an industrial process paper is protected by copyright, anyone not getting permission are not allowed to copy this paper, the author but the industrial process itself is not protected by copyright, it can be protected by patent.Another author can use his own language to describe the same industrial process and does not infringe the copyright of the authors.As for a story, novel, or whether the characters in the film are protected by copyright different court opinions.Copyright law in 1976 indicated:

Currently in the United States 70 years after the death of author owns the copyright, if work is a collective work or it is published before January 1, 1978, so its copyright from 75 to 95.Previously published work in 1923 are public domain.But there are exceptions to this rule, some work has entered into the public domain in 1963, while the other works of some of the early in 1923 to be copyrighted so still protected by copyright.Due to the change of law, by 2019 there will be no work into the public domain.