合理使用
Additionally, the fair use defense to copyright infringement was codified for the first time in section 107 of the 1976 Act. Fair use was not a novel proposition in 1976, however, as federal courts had been using a common law form of the doctrine since the 1840s (an English version of fair use appeared much earlier). The Act codified this common law doctrine with little modification. Under section 107, the fair use of a copyrighted work is not copyright infringement, even if such use technically violates section 106. While fair use explicitly applies to use of copyrighted work for criticism, news reporting, teaching, scholarship, or research purposes, the defense is not limited to these areas. The Act gives four factors to be considered to determine whether a particular use is a fair use: