This edition of the U. S. Department of Justice Antitrust Division Manual is the latest version of the day-to-day resource used by attorneys, economists, and other professionals of the Division to enforce this country's antitrust laws. This Fourth Edition incorporates changes in the statutes, guidelines, rules and other documents that govern the Division and reflect the Division's current practices and procedures. The Manual is an important resource for everyone at the Division, from seasoned attorneys with many years of practice to new paralegals fresh out of college. It answers many questions that can arise when conducting investigations or litigating cases.