The book includes an examination of sources of law important to addiction and its treatment. The foundations for forensic work in professional legal testimony is explored (e.g., legal system, case law precedent, statutes governing addictions, civil and criminal procedures). The science of addiction is featured including the biology of addiction, addiction as a brain disease, responsibility vs. loss of control, development of addictions, and the role of genetics and environment. Drug testing, its uses with forensic populations, what the tests show and do not show, controversies in using tests in the general population also receives extensive treatment. Addiction and mental illness in forensic populations is highlighted for addiction treatment and continuing care. Case studies and landmark cases illustrate the role of alcohol, drug use, and addictions in legal decisions.