Medical technologies often promise to extend and improve quality of life but come with many questions: Are they safe and effective? Are they worth the cost? When should they be allowed on the market, and when should Medicare, Medicaid, and private insurance companies be required to pay for drugs, devices, and diagnostic tests? Using case studies of disputes about the value of mammography screening; genetic testing for disease risk; brain imaging technologies to detect biomarkers associated with Alzheimer's disease; cell-based therapies; and new, expensive drugs, this book illustrates how scientific disagreements about what is good evidence of safety and effectiveness are often swept up in partisan fights over health care reform and battles among insurance and health care companies, physicians, and patient advocates. It reveals stakeholders' differing values and interests and clarifies the nature and complexity of past and current policy disagreements and their effects on patients.