Book excerpt: The Live Fire Test Law mandates realistic survivability and lethality testing of covered systems or programs. A provision of the law permits the Secretary of Defense to waive tests if live fire testing would be "unreasonably expensive and impractical." Though no waiver was requested before the F-22 program entered engineering and manufacturing development, the Defense Department later asked that Congress enact legislation to permit a waiver to be granted retroactively. Rather than enact such legislation, Congress requested a study to explore the pros and cons of full-scale, full-up testing for the F-22 aircraft program. The book discusses the origin of testing requirements, evaluates the practicality, affordability, and cost-benefit of live fire tests, and examines the role of testing, modeling, and data bases in vulnerability assessment.