The effects of drunk driving are a significant risk to public health and safety. Accordingly, the federal government and the states have enacted laws that permit law enforcement to identify offenders and to apply various levels of sanctions. There is no constitutional requirement that evidence of drunkenness be permitted in defense of criminal behavior. In practice, citizens who undertake to operate motor vehicles under the influence of alcohol are considered reckless per se and have no right to obstruct law enforcement in determining their condition. Indeed, refusal of roadside sobriety tests, including the Breathalyzer, may be considered a separate offense. The issuing of Miranda-type warnings by police officers has been ruled on recently in New Jersey. In a superior court appellate decision, State v. Spell, the court outlined the necessary procedures, concluding that, although motorists have no right to refuse testing, police officers have an obligation to issue sufficient warnings before the motorist decides how to proceed. In the Spell matter, the defendant incriminated himself by refusing the testing, even though he was acquitted on the drunk-driving charge. The authors discuss the role of expert testimony in these matters.