Here is a list of books that I strongly recommend reading to find out more about the issues surrounding US Copyright Law.
Copyright: The Complete Guide for Music Educators (2nd Ed.) by Jay Althouse
Moser on Music Copyright by David J. Moser
Music Copyright for the New Millenium by David J. Moser
Remix: Making Art and Commerce Thrive in the Hybrid Economy by Lawrence Lessig
Free Culture: The Nature and Future of Creativity by Lawrence Lessig
Copyrights and Copywrongs: The Rise of Intellectual Property and How it Threatens Creativity by Siva Vaidhyanathan
Digital Copyright by Jessica Littman
The Future of Music: Manifesto for the Digital Music Revolution by Gerd Leonhard and David Kusek
Copyright’s Highway: From Gutenberg to the Celestial Jukebox by Paul Goldstein
Copyright: Examples & Explanations by Stephen M. McJohn
Copyright: Plain & Simple by Cheryl Besenjak
Copy Fights: The Future of Intellectual Property in the Information Age Edited by Adam Thierer and Clyde Wayne Crews Jr.
Fair Use, Free Use and Use By Permission: How To Handle Copyrights in All Media by Lee Wilson
Internet Surf and Turf Revealed: The Essential Guide to Copyright, Fair Use, and Finding Media by Barbara M. Waxer and Marsha L. Baum
Bound By Law (Tales from the Public Domain) by Keith Aoki