The National Institute of Justice is pleased to release DNA for the Defense Bar. This is the fourth publication in a series designed to increase the field's understanding of the science of DNA and its application in the courtroom. The other three publications include "Principles of Forensic DNA for Officers of the Court," "DNA: A Prosecutor's Practice Notebook," and "DNA for Law Enforcement Decision Makers." This book is specifically designed for criminal defense attorneys. You are defense counsel in a case with DNA evidence or where the absence of DNA evidence may raise factual or legal issues. DNA evidence, when properly collected and analyzed, and when relevant to an alleged crime, can have extraordinary value in the adjudication of a criminal case. This book is designed to help defense attorneys understand: The biology of DNA, Proper collection procedures for DNA evidence, Interpretation of DNA analysis and findings, When and why an expert is needed, Development of case theory in a DNA-based prosecution or in a case where there should be DNA evidence, Legal issues for pretrial and trial in cases with DNA evidence.