I. United States
Copyright law in the U.S. is administered by the United States Copyright Office,
which is part of the Library of Congress. The Office's Web site is a good central source for U.S. Copyright information.
Registering a Copyright / Recording a Transfer: In the U.S., a person who creates an original work automatically gets a copyright in the work on creation. The author may then choose to register the copyright with the Library of Congress Copyright Office to establish a record of ownership. Basically this entails filing a form (online or on paper) and paying a fee. The Copyright Office posts the necessary information at www.copyright.gov/eco/.
The Copyright Office posts information on how to record a transfer of copyright ownership.
Researching Registration Records: You can search for copyright registration records back to 1978 through the Copyright Office's Public Copyright Catalog page. You can also use Lexis (COPYRIGHT;ALLCPY), which also searches legal documents sent to notify the Copyright Office of subsequent transfers of copyright ownership.
For older copyrights, you can search or browse scans of the Catalog of Copyright Entries included in Google Books (1923-1977). Alternatively, you can manually search the Catalog in print if an edition is available in a local library (check Worldcat) or online from the Internet Archive. In print, the Catalog is an eight volume set, published quarterly. Each volume corresponds to one type of work (movies, maps, sound recordings, etc.). The records are arranged by title and author, so it helps to know the registration date and type of work.
You might also want to check OCLC's Copyright Evidence Registry to see if someone has commented on the copyright status of a work.
A number of private firms do specialized copyright research, including manual searches at the Library of Congress covering registrations back to 1870. Two big research firms are Government Liaison Services (800-642-6564) and the copyright department at Thomson CompuMark (800-692-8833 or 800-356-8630).
You can search to see if a copyright has been assigned to a new owner using the same Public Copyright Catalog you use to look up registrations. The database goes back to 1978. To look for transfers before then, you have to look in the Assignment and Related Documents Index, which covers 1870-1977.
Laws and Regulations: The U.S. Copyright Law is published as Title 17 of the United States Code and the related regulations are published in Title 37 of the Code of Federal Regulations. The full text of Title 17 is posted on the Copyright Office's Copyright Law page. The Compendium of U.S. Copyright Office Practices is the administrative manual of the Register of Copyrights concerning Title 17 of the United States Code and Chapter 37 of the Code of Federal Regulations. The current 3rd edition (2014) of the Compendium is available on the Copyright Office website.
The subscription-based Intellectual Property Law Collection on HeinOnline has pre-compiled legislative histories for U.S. copyright laws.
If you need to get a grip on practical copyright law, there are many copyright law primers and summaries available including the About Copyright section of the Library of Congress' Copyright page, Copyright Basics by the University of Connecticut Libraries and the Overview by Nolo posted by the Stanford University Libraries' Copyright and Fair Use Center.
Perhaps the trickiest and most important exception to copyright is "Fair Use" (17 U.S.C. 107). For guidance in applying Fair Use, see the Fair Use chapter of the Nolo overview posted by the Stanford University Libraries' Copyright and Fair Use Center and/or the Fair Use Tools & Guidelines collected by the University of Connecticut Library. For case law interpreting fair use, see the Copyright Office's Fair Use Index. Also useful: the Fair Use Checklists posted by Indiana University-Purdue University Indianapolis, the University of Georgia and many other libraries, and the related Thinking Through Fair Use tool by the University of Minnesota Libraries.
Treatises: The leading treatise on copyright law is Nimmer on Copyright: A Treatise on the Law of Literary, Musical and Artistic Property, and the Protection of Ideas (Lexis/Matthew Bender).
Works in the Public Domain: To determine whether a work has passed into the public domain under U.S. law, see How to Investigate the Copyright Status of a Work by the Copyright Office. For charts showing the various copyright terms, see Copyright Term and the Public Domain in the United States by Peter Hirtle and/or When U.S. Works Pass Into the Public Domain by Lolly Gasaway of the University of North Carolina. Note: To be safe, check the charts against current law before relying them.
When you actually search to see if a work is in the public domain, you will want to find both the original registration record and any renewal records, which could extend the life of the copyright. Renewal records filed from 1978 to the present are included in the Copyright Office's Search Copyright Records database. If you need to search back further, Google has loaded renewal records in bulk into Google Books.
Thomson Compumark offers a product called "U.S. Copyright Duration Report" which is designed to tell you how long a copyright's protected status lasts.
II. Foreign and International
English language translations of the copyright laws from many countries are published in Copyright Throughout The World (West), Copyright and Neighboring Rights, Laws and Treaties (WIPO) and WIPO Lex (CLEA).
The Canadian Intellectual Property Office posts very good information about Canadian copyrights, including the full text of the Canadian Copyright Act, the related regulations, circulars, tariff information, etc.
For more resources see "Foreign Laws." See also the "Treaties" section, below.
III. Other Information
Arbitration: The Copyright Office CARP and Licensing Information Web page (http://lcweb.loc.gov/copyright/carp/) posts the Rules and Regulations of the Copyright Arbitration Royalty Panels
and a lot of other information related to copyright arbitration. See also "Arbitration."
Copyright Royalty Board: The Copyright Royalty Board (CRB) oversees "statutory licenses." Statutory licenses "make it possible for qualified parties to use multiple copyrighted works without obtaining separate licenses from each copyright owner." So, for example, the judges on the Board set the royalty rates to be paid by Internet radio stations for playing copyrighted sound recordings. The relevant laws, regulations, Orders and additional information are all available on the Board's web site (www.loc.gov/crb/laws/).
Circulars: The U.S. Copyright Office posts its current Copyright Information Circulars and Fact Sheets. You can get superseded Circulars by calling the Copyright Office.
For Law Librarians: A good source for copyright information is the AALL's Copyright Resources page. To get many copyright licenses at once you can, for a hefty fee, sign on with the Copyright Clearance Center. You can also negotiate licenses individually, by working with individual publishers, or through companies such as iCopyright. See also the "Laws and Regulations" section, above.
Forms: U.S. Copyright Office Forms are posted at www.copyright.gov/forms/.
License Agreements: You can get sample copyright license agreements -- or look up agreements by a public company -- using Lexis Securities Mosaic, GSI Online or another database that searches exhibits to SEC filings (see the "Filings" section of the Securities and Exchange Commission entry).
Other Internet Sites: The AALL provides useful information about Copyright Resources. Stanford University's Copyright and Fair Use has links to important copyright websites, as well as important cases (sometimes including briefs and analysis) and legislation.
Permissions: Copyright.com, from the Copyright Clearance Center, lets you get permissions to use a wide range of copyrighted works.
Research Services: See "Researching Registration Records," above.
Treaties: The Universal Copyright Convention (U.N.T.S. No. 13444), the World Intellectual Property Organization: Copyright Treaty (36 I.L.M. 65), the Berne Convention and other key copyright treaties are posted by WIPO Lex. You an also find U.S. copyright treaties in the Appendices to Circular 92 by the U.S. Copyright Office and on Lexis (COPYRT;TREATY).
See also the separate entries for "Treaties - U.S." and "Treaties - Foreign."