Article I section 8 of the Constitution provides the basis for all copyright law in the United States:

The Congress shall have Power…To promote the Progress of Science and useful Arts, by securing for limited Times to Authors and Inventors the exclusive Right to their respective Writings and Discoveries.

Congress did their thing and passed successive version of laws regarding the rights of authors and the rights of other to make copies that have been recorded in Title 17 of the United States Code. The current 2003 version 290 page pdf document published as Circular 92 of Title 17. This document includes all sorts of law but seems based primarily on the 1976 Copyright Act the Digital Millenium Act and a few foreign trade agreements like GATT and NAFTA.

Works in the public domain can't be copyrighted and include those published before 1923, US Government publications, and other documents as their copyrights expire. In 1976 Congress decided 70 years after the author(s) death was appropriate. Lolly Gasaway at UNC offers a bit more about works passing into the public domain in a nice table showing all the cases.

What Is Copyright?

Simply put, "copyright is a legal device that provides the creator of a work of art or literature, or a work that conveys information or ideas, the right to control how the work is used." Stephen Fishman, Esq. The Copyright Handbook, 1996.

The intent of copyright is to advance the progress of knowledge by giving an author of a work an economic incentive to create new works.

What Can be Copyrighted?

Tangible, original expression. This means, for example, that a verbal presentation that is not recorded cannot be copyrighted. However, anything that is tangible can be copyrighted. There are three fundamental requirements for something to be copyrighted:

• Fixation:
  • The item must be fixed in some way. The fixation may be just about anything. For example, a piece of paper, a computer disk, a audiotape, or a videotape are all legitimate forms of fixation.
• Originality:
  • The work must be original. Originality includes a novel or a student's e-mail message to a professor. Both are considered examples of original expression.
  • It is not necessary for the work to be completely original. Works may be combined, adapted, or transformed in new ways that would make them eligible for copyright protection.
• Minimal Creativity:
  • The work must include something that is above and beyond the original. Verbatim use is not considered original. Reference to the original work that is used to discuss a new concept would be considered original, however.
  • Creativity need only be extremely slight for the work to be eligible for protection.

What Cannot be Copyrighted?

• Works in the public domain:
  • Ideas are in the public domain. (this one gave fits to the early computer programmers as their algorithms were considered ideas...they tried patents and then used copyright on the entire programs. Mostly they just tried to keep their stuff secret by not distributing the source code.)
    
  • Facts are in the public domain.
  • Words, names, slogans, or other short phrases also cannot be copyrighted. However, slogans, for example, can be protected by trademark law.
  • Blank forms.
  • Government works, which include:
    • Judicial opinions.
    • Public ordinances.
    • Administrative rulings.
  • Works created by federal government employees as part of their official responsibility.
  • Works for which copyright wasn't obtained or copyright has expired (extremely rare!).

It is a common misperception that state employees and contractors performing work on behalf of the federal government cannot copyright their work. Unless it is explicitly stated in the contract between the government and a contractor, federal government contractors are permitted to copyright their works as can state employees.

What Does Copyright Protect?

Copyright provides authors fairly substantial control over their work. The four basic protections are:

• The right to make copies of the work.
• The right to sell or otherwise distribute copies of the work.
• The right to prepare new works based on the protected work.
• The right to perform the protected work (such as a stage play or painting) in public.

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An Introduction to Fair Use

What is Fair Use?

Fair use is the most significant limitation on the copyright holder's exclusive rights. Deciding whether the use of a work is fair IS NOT a science. There are no set guidelines that are universally accepted. Instead, the individual who wants to use a copyrighted work must weigh four factors:

The purpose and character of the use:

• Is the new work merely a copy of the original? If it is simply a copy, it is not as likely to be considered fair use.
• Does the new work offer something above and beyond the original? Does it transform the original work in some way? If the work is altered significantly, used for another purpose, appeals to a different audience, it more likely to be considered fair use.
• Is the use of the copyrighted work for nonprofit or educational purposes? The use of copyrighted works for nonprofit or educational purposes is more likely to be considered fair use.

The nature of the copyrighted work:

• Is the copyrighted work a published or unpublished works? Unpublished works are less likely to be considered fair use.
• Is the copyrighted work out of print? If it is, it is more likely to be considered fair use.
• Is the work factual or artistic? The more a work tends toward artistic expression, the less likely it will be considered fair use.

The amount and substantiality of the portion used:

• The more you use, the less likely it will be considered fair use.
• Does the amount you use exceed a reasonable expectation? If it approaches 50 percent of the entire work, it is likely to be considered an unfair use of the copyrighted work.
• Is the particular portion used likely to adversely affect the author's economic gain? If you use the "heart" or "essence" of a work, it is less likely your use will be considered fair.

The effect of use on the potential market for the copyrighted work:

• The more the new work differs from the original, the less likely it will be considered an infringement.
• Does the work appeal to the same audience as the original? If the answer is yes, it will likely be considered an infringement.
• Does the new work contain anything original? If it does, it is more likely the use of the copyrighted material will be seen as fair use.

These excerpts starting with "What is Copyright" are from a copyrighted webpage maintained by the University of Maryland University College as guidelines for their faculty.(click link to see their site).