Are There Exceptions to Copyright Law?
There are only a few exceptions to the exclusive rights granted to copyright holders. The one most commonly used in education is called "Fair Use."
The Fair Use exception in copyright law allows limited uses of another's work without approval, for criticism, commentary, news reporting, home use, education and research.
Fair use in education means that faculty and students in schools and libraries can use limited portions of copyrighted works for nonprofit instruction, research or scholarly activities.
Fair Use is commonly used to allow copying/scanning and distribution of short sections of copyrighted works in colleges and universities.
Fair Use also requires crediting original artists or authors.
Fair Use is complex and limited.
Any Other Exceptions?
Other than Fair Use, there are few legal ways to get around copyright restrictions. Claiming that you did not know something was copyrighted, or assuming that the author wouldn't mind your use of his/her material, are not valid defenses.
The perfect example is artist Shepard Fairey's derivative work based on a photograph taken by photographer Mannie Garcia of Barrack Obama during his first campaign.