The prosecutor in a criminal case must prove every element of the offense beyond a reasonable doubt in order to obtain a conviction. If the prosecutor leaves one or more jurors with reasonable doubt about the defendant’s guilt, he or she must be found not guilty.  Our criminal justice system is built upon the premise of proof beyond a reasonable doubt.

Like every other criminal prosecution, a DUI / DWI case is proven through the elements of the offense. Every criminal prosecution, including drunk driving and driving under the influence of drugs (DUID), depends on the prosecutor’s ability or inability to prove every element of the offense beyond a reasonable doubt.  If any juror harbors reasonable doubt about the driver’s guilt, he or she must be acquitted.

The elements of a DUI / DWI offense vary from state to state. In many states, the offense of drunk driving is made up of two elements – driving under the influence or driving while impaired, and violating the state’s “per se” law. Per se is just another way of saying that the driver is accused of having a blood alcohol content (BAC) of .08 percent or greater – now the legal limit in all 50 states. In some states, the prosecutor must prove both elements to get a conviction, and in other states only one element must be proven.

In other states, a DUI / DWI triggers two separate charges – driving under the influence and violating the per se laws. The first charge, driving under the influence, focuses on whether or not the motorist was too impaired to drive safely. Although the prosecutor may opt to use the driver’s BAC as evidence in a driving under the influence case, the focus is on the driver’s degree of impairment.

Some states break the offense of driving under the influence down into additional elements. In a few states, the prosecutor must prove that the motorist was driving or operating a vehicle. This is less obvious than it seems – sometimes motorists are arrested for DUI / DWI after being discovered asleep in a parked vehicle or one that is inoperable. And the definition of what constitutes a “vehicle” varies from state to state.

A driver accused of DUI / DWI also will be charged with violating the state’s per se laws by having a BAC of .08 percent or greater. Prosecutors use chemical test results to prove this allegation.