Driving under the influence (DUI) in Idaho is governed primarily by Idaho Code §18-8004 and related statutes. These laws make it illegal to operate or be in actual physical control of a motor vehicle while impaired by alcohol, drugs, or a combination of both.

Although DUI laws exist in every state, Idaho's statutes have some unique features, including a separate category for “excessive DUI” and strict rules governing driver's license suspensions.

For someone who has never been through the criminal justice system before, the process can feel confusing and intimidating. Understanding how Idaho DUI law works is the first step toward making informed decisions about your case.

What Counts as a DUI in Idaho?

In Idaho, a person can be charged with DUI in several ways.

BAC of .08 or Higher

The most common DUI charge arises when a driver's blood alcohol concentration (BAC) is 0.08 or higher.

For commercial drivers, the threshold is 0.04.

For drivers under 21, the limit is 0.02.

Impairment by Alcohol or Drugs

A person may also be charged with DUI if they are impaired by alcohol, drugs, or a combination of substances, even if their BAC is below .08.

This means that prescription medications, marijuana, or illegal drugs can also lead to a DUI charge if they impair a person's ability to drive safely.

Actual Physical Control

Idaho law does not require a person to be actively driving to be charged with DUI.

If someone is in “actual physical control” of a vehicle while impaired, they can still be charged. Courts often interpret this broadly and may consider factors such as:

  • whether the person was in the driver's seat

  • whether the vehicle was running

Excessive DUI in Idaho

Idaho law creates a separate offense called excessive DUI, which applies when a driver's BAC is 0.20 or higher.

Excessive DUI carries more severe penalties, including mandatory jail time and longer license suspensions.

Because of these consequences, excessive DUI charges often receive closer scrutiny from defense attorneys and prosecutors.

Repeat DUI Offenses

Idaho increases penalties for repeat DUI convictions within a 10-year period.

A third DUI within ten years is treated as a felony offense, which can carry the possibility of prison time.

License Suspension and Administrative Penalties

In addition to criminal penalties, Idaho DUI arrests often trigger administrative license suspensions through the Idaho Transportation Department.

Drivers typically have a very short window to challenge these suspensions, which is why many people seek legal advice shortly after an arrest.

DUI Charges Are Fact-Specific

Every DUI case depends on the specific facts involved, including:

  • BAC level

  • prior convictions

  • whether an accident occurred

  • whether anyone was injured

Because these factors can significantly affect the outcome of a case, DUI charges should be carefully reviewed before decisions are made about how to proceed.

Frequently Asked Questions About Idaho DUI Law

What blood alcohol level is considered DUI in Idaho?
In Idaho, a person can be charged with DUI if their blood alcohol concentration (BAC) is 0.08 or higher. Commercial drivers may be charged with DUI at 0.04, and drivers under age 21 may be charged at 0.02. A person can also be charged with DUI if they are impaired by alcohol, drugs, or a combination of substances even if their BAC is below the legal limit.

Can you be charged with DUI if your BAC is below .08 in Idaho?
Yes. Idaho law allows DUI charges if a driver is impaired by alcohol, drugs, or other substances, even if their BAC is below 0.08. In these cases, prosecutors typically rely on officer observations, driving behavior, and field sobriety test results.

What is an “excessive DUI” in Idaho?
An excessive DUI occurs when a driver's BAC is 0.20 or higher. Idaho law imposes enhanced penalties for excessive DUI, including mandatory jail time and longer license suspensions.

About the Author

Cody Long is a criminal defense attorney who has defended DUI cases in Idaho for more than 20 years. If you are facing a DUI charge in Boise, Meridian, Nampa, Caldwell or anywhere in southwest Idaho, contact Long Law Office for a consultation.