Collection, preservation, and packaging procedures are outlined, as are methods of taking the blood sample, and the instrumental, chemical, and enzymatic techniques of laboratory analysis. Special considerations for obtaining blood alcohol levels post-mortem are presented. Portable instruments, such as the breathalyzer, are available and greatly reduce the time required to determine intoxification. The accuracy of the breathalyzer is confirmed in a review of various studies. When a person may be charged with culpable driving the police must question the suspect on drinking and drug habits in order to enable experts to better estimate the blood alcohol levels at the time of the accident or incident and give an opinion as to whether the subject was under the influence. The alcoholic content of liquor, the number of drinks to become intoxicated, and the metabolism of alcohol are discussed. The effects of alcohol and determination of the degree of impairment of driving ability are examined. The Warwick Farm Experiment is discussed. The role of the courts and breathalyzer operators as expert witnesses are examined. An appendix provides a glossary of blood alcohol analysis and their addresses. Twenty-seven references are appended.