What is the difference between an OUI and a DUI in Illinois?

In Illinois, it is illegal to operate virtually any time of motor vehicle while under the influence of drugs or alcohol.  The two most commonly operated vehicles that are most often cited are the use of boats and automobiles.  Although both are illegal, they are governed by different laws and have some key differences.


The law governing operating a watercraft is found under the Boat Registration and Safety Act.  Section 5-16 of this law prohibits the operation of a watercraft while under the influence of drugs or alcohol.  The permissible blood alcohol concentration (BAC) level noted in the law is the same as for operating an automobile, which is below .08.  However, the law forbids operating a watercraft under the influence of drugs or alcohol at all.

The first OUI violation is a Class A misdemeanor.  This offense become a Class 4 felony if it is not the first OUI, the offense was committed while watercraft privileges were suspended, or a personal injury resulted as a result of operating under the influence.

Similar to the laws governing DUI, the statute is written to give law enforcement implied consent to submit to a chemical test to determine BAC or discover other intoxicating substances in the bloodstream.  This consent can be revoked, but refusal to consent to the chemical test will result in suspension of watercraft operation privileges for a minimum of 2 years.

Other differences between OUI and DUI are the difference in field sobriety tests and which branch of law enforcement investigates OUI offenses.  Since it is hard to administer the standard field sobriety tests associated with DUI without a solid surface, law enforcement will likely use different tests.  These include the HGN eye test, the Alphabet test, and the Finger to Nose test.  Also, the law enforcement entity that investigates OUI is the Conservation Police, which is a branch of the Illinois Department of Natural Resources.


In contrast, DUI offenses are governed by the Illinois Vehicle Code.  The permissible BAC level to avoid this offense is under .08.  Unlike OUI, the first and second DUI is still considered a misdemeanor.  Factors that influence whether additional penalties will be attached include a BAC of .16 or higher, having a minor in the car at the time of the offense, and if the offense qualifies as an aggravated DUI charge.

It is not until the third DUI offense that a felony results.  The third and fourth offense is considered a Class 2 felony.  A fifth offense is considered a Class 1 felony.  The sixth offense and beyond is considered a Class X felony, which carries the stiffest legal sanctions in the state (with the exception of murder).

Like OUI, the DUI law has a section for implied consent.  It operates in the same manner as the OUI law in that consent can be refused to submit to a chemical test to determine drug or alcohol levels in the bloodstream.  However, the minimum mandatory suspension times vary depending on the circumstances of the case.

Whether you are accused of DUI or OUI, the assistance of a qualified Illinois Criminal Defense Attorney is highly recommended.

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