For a print version of many of the legal sources identified below plus updates on recent cases, consider purchasing the Casebook Supplement.  The 2015 edition is available here.  The 10th edition of the casebook is in production and will be published in 2016.

United States

• The Copyright Act of 1976, as amended, and related provisions in Title 17 United States Code (also published as U.S. Copyright Office Circular 92)
• U.S. Copyright Office Regulations, 37 C.F.R. 201 et seq. (also published as U.S. Copyright Office Circular 96)
• U.S. Copyright Royalty Review Board Regulations, 37 C.F.R. 301 et seq.
• U.S. Customs and Border Patrol Customs Directive No. 2310-005B Copyright Protection

Other U.S. Legal Resources

• House Report No. 94-1476 (1976) (principal source of legislative history for the original 1976 Act)
• The Compendium of U.S. Copyright Office Practices (3rd ed., Dec. 22, 2014) is a guide for examiners and those seeking copyright registration, among others. The Copyright Office also hosts scanned versions of the first (1973) and second (1984) editions of the Compendium.
• For a historical look at the Copyright Act since 1909, see this site maintained by Attorney David Hayes.
• For proposed legislation, see here.
• U.S. Copyright Office rulemaking proceedings.
• U.S. Copyright Office Reports and Studies

International

Treaties to which the United States is a Contracting Party

• Buenos Aires Convention (1910)
• Berne Convention for the Protection of Artistic and Literary Works, as revised (1979).
• Universal Copyright Convention, as revised (1971)
• Convention for the Producers of Phonograms Against Unauthorized Duplication of Their Phonograms (1971)
• Convention Relating to the Distribution of Programme-Carrying Signals Transmitted by Satellite (1974)
• TRIPS Agreement – (formally The Agreement on Trade-Related Aspects of Intellectual Property (TRIPS), Annex 1C of the Marrakesh Agreement Establishing the World Trade Organization (1994))
• WIPO Copyright Treaty (WCT) (1996)
• WIPO Performances and Phonograms Treaty (WPPT) (1996)
• For breakdown of the United States’ international copyright relations by country, including countries with which the United States has a bilateral agreement or a trade agreement with copyright-related obligations, see Copyright Office Circular 38

Treaties to which the United States is not a Contracting Party

• International Convention for the Protection of Performers, Producers of Phonograms and Broadcasting Organizations (Rome Convention) (1961)
• Beijing Treaty on Audiovisual Performances (2012) (signed but not ratified)
• Marrakesh Treaty to Facilitate Access to Published Works for Persons Who Are Blind, Visually Impaired, or Otherwise Print Disabled (2013) (signed but not ratified)