The American Legal System: Foundations, Processes, and Norms (Roxbury Publishing Co., 2003) was written by Albert Melone, professor of political science at SIUC, and Allan Karnes, professor and director of SIUC's School of Accountancy, to answer questions big and small about U.S. jurisprudence. Intended for students in fields from business to criminal justice and political science, it's very approachable for general readers too.