Plagiarism is the reproduction, in whole or essential part, of a manifestation of intellectual endeavor - such as a book, a statue, or a symphony - by someone who holds himself out as its creator, but is not. The infraction is not theft of the work itself, but false representation as to source. However, the use of themes and ideas common to every educated man is considered inevitable, and is not plagiarism. The mere treatment of a subject identical with that dealt with by someone else is not forbidden either. What may not be adopted is the other person's unique method of treatment. The copy need not be identical to be a plagiary; so long as the essence of the original is used, the offense is committed.
The law safeguards an artist from certain acts of plagiarism. Until he makes his handiwork available to the general public, he has an absolute legal protection from any unauthorized use. In almost every country there are statutes and treaties giving artists the exclusive right to exploit their products publicly, but for a limited period of time. Plagiarism of an object protected by such laws is punishable by civil and criminal penalties.
In the United States, limited unauthorized use of copyrighted material without acknowledgment of source is permitted under the doctrine of fair use. What constitutes fair use is not clearly defined by the courts. Whether the use adversely affects the statutory rights of the copyright holder is the principal inquiry made in deciding the matter.