A DUI arrest starts two separate cases on two different clocks, and most people discover the second one after it is too late to contest. This article explains the criminal case and the administrative license case, why the deadline to request a license hearing is measured in days, and how the two interact. It covers the stop and the reasonable suspicion required for it, the expansion into an impaired driving investigation, and what the field sobriety tests actually measure. It explains implied consent, the consequences of refusal, and why Birchfield-era doctrine distinguishes breath from blood. It covers Schmerber, Mitchell v. Wisconsin, and the warrant question for blood draws. It explains the per se limit and what a chemical test result does and does not establish. It covers the administrative hearing, the limited issues, and why it is worth having anyway. It closes with plea considerations, collateral consequences, and eleven ways cases are made worse.