A significant revision of the impaired driving statutes occurred during the 1981-82 session of the Wisconsin Legislature (Chapter 20, Laws of 1981). That revision is the substantive core of present law, although a number of changes have been enacted in the interim. This paper reviews the major changes enacted through Chapter 20, Laws of 1981. These include establishing 0.1 percent or more blood alcohol concentration as a per se drunk driving violation, requiring drivers convicted of drunk driving or improperly refusing to take a chemical test to submit to an assessment of their use of alcohol or drugs and to submit to alcohol or drug treatment, and increasing and altering the penalty structure. One part of the memorandum describes the basic elements of and penalties for the various violations involving DWI. Other sections of the memorandum discuss the Implied Consent Law, administrative suspension for high-level chemical tests, intoxicants in motor vehicles, and selected laws relating to OWI in other States. 2 tables.