This work provides a comprehensive guide to an increasingly complex area of law. It adopts a problem solving focus, combining the relevant legislation and case law with an explanation of the scientific terms and material used in prosecuting a drink driving case. This second edition has completely updated, with emphasis on two innovations. Firstly, the case of Warren (where the House of Lords laid down the correct procedure to be followed for obtaining blood or urine) and how it has been discussed. Secondly, there is in-depth coverage of the case of Shephard which held that section 69 of PACE applies to all computers; this has has implications for the use of breathalyzers. Also explored is the response by the Director of Public Prosecutions. A chapter on Causing death by careless driving when driving under the influence has been included in this edition.