Copyright as a legal concept in the United States has its roots in the United States Constitution in Article 1 Section 8, Clause 8: " 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."
Title 17 of the United States Code  provides the laws that further define copyright.
Title 17 grants the owners of copyright exclusive rights to reproduce, perform, distribute and license their works for a limited time. Current law requires no official copyright registration, defining as copyrighted from 1989 on "any original works of authorship fixed in any tangible medium of expression, now known or later developed, from which they can be perceived, reproduced, or otherwise communicated, either directly or with the aid of a machine or device."
Fair Use and other exceptions to the Copyright Laws
Some documents are not copyrighted at all. A work may have passed into the public domain (see chart for dates ).
Or it may be a government document, a collection of facts or freeware. These may all be used without copyright permission.
The majority of acceptable free use of copyrighted materials for educational purposes exists in limitations to the law, found in Title 17, Chapter 1, Sections 107 and 108. Generally, the most useful limitation of copyright for disseminating materials for pedagogical use falls under the Fair Use Doctrine.
It is important to note that the Fair Use Doctrine provides no hard-and-fast rules to gauge fair use. Case law has done little to clarify fair use. And the Internet has added chaotic elements to an already ambiguous set of standards.
All four factors in the Fair Use Doctrine must be taken into consideration on a case-by-case basis to decide if a work falls within fair use.
Section 107 sets out four factors that must be used to ascertain fair use.
1. The purpose or character of the use
2. The nature of the copyrighted work being used
3. The amount and substantiality of the work being used
4. The effect of the use on the market for or value of the original
Licensing has serious implications for the concept of fair use. The model of licensing electronic information has become the industry standard. The majority of electronic information available through libraries is leased rather than owned. In this environment license agreements take on profound implications as contracts are legally binding, regardless of where they fall in our interpretations of fair use.
A number of organizations have created guidelines to address questions raised by the copyright laws. Each guideline represents a viewpoint that accords to some degree with the purposes of the individual organization. None of the guidelines have been tested by a court case, and none of them have the force of law. Why then would individuals and organizations utilize them?
The penalties for willful copyright infringement are quite high. Infringement from ignorance of the law also carries financial penalties, and in both cases legal fees may also be expensive. However, within Title 17 exists a clause that excuses those who "had reasonable grounds for believing that his or her use of the copyrighted work was a fair use under section 107 ."
Following an organizational guideline on copyright procedures would serve as proof that you acted in good faith when applying the fair use doctrine.
The Association of Research Libraries (ARL) Code of Best Practices in Fair Use for Academic and Research Libraries (PDF) 
Model Policy Concerning College and University Photocopying for Classroom, Research and Library Reserve Room Use 
American Library Association
The American Library Association issued this policy in response to the Copyright Law that took effect in 1978. Much of the basic material is out-of-date. However, many organizations have adapted the guidelines to include electronic delivery of materials.
Fair Use in the Electronic Age (Working Document) 
Association of Research Libraries, in conjunction with several other library associations
While not strictly guidelines, this working document updates the philosophy of the American Library Association guidelines. It promotes a liberal interpretation of fair use, but has less force to it than official guidelines would.
Under the Clinton administration the U.S. Patent and Trademark Office facilitated the Conference on Fair Use (CONFU). CONFU involved over 100 organizations representing both holders and users of copyrighted materials. It ran over two years, and in the end failed produce an official set of guidelines. However, drafts of guidelines were produced and provide a starting point to create other guidelines. Basically the publishing industries found the guidelines too liberal and the educational community found them too conservative. For an analysis of the draft guidelines see the Association for Research Libraries commentary .
Basic Principals for Managing Intellectual Property in the Digital Environment 
NINCH (National Initiative for a Networked Cultural Heritage) and National Humanities Alliance
Created by a group of organizations that promote educational uses of information, these principals contain a somewhat liberal bias towards interpreting and creating copyright laws. They could be used as a basis to form guidelines.
Guidelines on photocopying under Interlibrary Loan Arrangements 
CONTU (National Commission on New Technological Uses of Copyrighted Works)
Created in 1978 with by the Commission to aid congress in writing a new copyright act. These guidelines only apply to
interlibrary loan and were agreed upon by library, publisher and author organizations. Out-of-date for electronic materials,
at least the guidelines stand as something once agreed upon by the publishing and educational communities.
Image Collection Guidelines: The Acquisition and Use of Images in Non-Profit Educational Visual Resources Collections
Visual Resources Association