Idaho’s excessive-DUI law applies when the state proves an underlying DUI and a police-requested analysis of breath, blood, or urine shows an alcohol concentration of 0.20 or more. When the current case is the person’s first DUI violation, section 18-8004C(1) classifies it as a misdemeanor, but it carries mandatory jail and a much longer absolute license suspension than an ordinary first DUI.
A high test result does not erase the other elements of the case. The state must still prove that the accused drove or was in actual physical control of a motor vehicle in a place covered by Idaho law and committed the underlying DUI offense. The 0.20 result is what activates the enhanced penalty statute, Idaho Code section 18-8004C.
If you were served with a failed-test license notice, there may also be a separate seven-calendar-day deadline for an administrative hearing. Read the firm’s guide to an Idaho administrative license suspension and keep every page of the notice.
Idaho excessive DUI penalties at a glance
| Issue | First DUI violation with a 0.20-or-higher result | Repeat excessive DUI within five years |
|---|---|---|
| Classification | Misdemeanor | Felony, if both the current and qualifying prior violations involved a 0.20-or-higher result |
| Custody | Mandatory minimum 10 days; first 48 hours consecutive; maximum 1 year | State correctional custody up to 5 years; if the court does not impose penitentiary incarceration, mandatory minimum 30 days in county jail |
| Fine | Up to $2,000 | Up to $5,000 |
| Court-ordered license suspension | Mandatory minimum 1 year after release from confinement, with no ordinary driving privileges | Mandatory minimum 1 year and up to 5 years after release from imprisonment, with no ordinary driving privileges |
| Ignition interlock | Interlock-restricted driving follows the suspension | Interlock-restricted driving follows the mandatory suspension |
These are statutory ranges, not a prediction of a sentence. Court costs, probation conditions, treatment, insurance consequences, and a separate administrative suspension can add other obligations. A narrow problem-solving-court exception to the absolute driving period is discussed below.
What the state must prove
Idaho Code section 18-8004C does not create liability from a laboratory number alone. For a person’s first DUI violation, subsection (1) applies when the person pleads guilty to or is found guilty of the underlying DUI defined in section 18-8004(1)(a) and the police-requested test shows 0.20 or more.
The current Idaho criminal jury instructions separate those issues. The underlying instruction requires proof of driving or actual physical control, a motor vehicle, a covered location, and the charged alcohol or impairment theory. The state must prove each required element beyond a reasonable doubt.
The statute measures alcohol concentration as grams of alcohol per 100 cubic centimeters of blood, 210 liters of breath, or 67 milliliters of urine. A roadside handheld screening result is not automatically the evidentiary result on which an excessive-DUI charge rests. Identify the particular instrument or laboratory analysis alleged in the charging document and discovery.
The five-year felony rule requires a prior 0.20-or-higher violation
A current 0.20-or-higher result does not become a felony merely because the driver has any earlier DUI. Under section 18-8004C(2), the special excessive-DUI felony applies when:
- the current case includes an underlying DUI and a police-requested test showing 0.20 or more; and
- within five years, the person previously pled guilty to or was found guilty of an Idaho DUI in which the alcohol concentration was also 0.20 or more, or a substantially conforming foreign violation with that same high-concentration feature.
The statute counts a qualifying prior notwithstanding the form of the judgment or a withheld judgment. Idaho’s pattern special-verdict instruction also treats the prior high-concentration allegation as a question the state must prove beyond a reasonable doubt when it is contested.
A prior DUI at a lower alcohol concentration does not satisfy that specific five-year excessive-DUI felony rule. It may still trigger Idaho’s general repeat-DUI provisions, including the separate second-offense DUI law. The dates, statutes, test results, and final disposition of each alleged prior should be checked rather than relying on a label in a driving-record summary.
License consequences involve two different cases
An excessive-DUI allegation can create both a criminal-court suspension and an administrative suspension through the Idaho Transportation Department:
- Criminal suspension. A first-DUI 0.20-or-higher conviction carries at least one year of absolute suspension after release from confinement. A qualifying repeat excessive-DUI felony carries one to five years of absolute suspension after release from imprisonment.
- Failed-test ALS. A completed evidentiary test can start a separate administrative action under Idaho Code section 18-8002A. A first failed test produces a 90-day ALS, with the first 30 days absolute; a second or later failed test within five years produces a one-year ALS with no ordinary restricted permit.
The ALS count is based on failed evidentiary tests, not simply the number of criminal DUI convictions. The two suspension periods arising from the same event generally run concurrently up to the longer applicable period unless the criminal court orders otherwise, but both orders still must be satisfied. Do not drive based on a calendar estimate; verify the current status with ITD.
Sections 18-8004C(3) and 18-8005 provide a narrow exception for a participant in good standing in an approved drug court, mental health court, or similar problem-solving court. After at least 45 days of absolute suspension, the presiding judge may grant restricted noncommercial privileges for specified work, school, or treatment travel if the statutory interlock and financial-responsibility conditions are met. This is not an ordinary hardship permit and is not available merely on request.
Ignition interlock follows the suspension
After the applicable suspension, Idaho law requires the person to drive only a vehicle equipped with a functioning state-approved ignition interlock system. A 2026 amendment to Idaho Code section 18-8008, effective July 1, 2026, provides that the interlock restriction ends one year from the date the vendor provides proof of installation to ITD.
Delaying installation can therefore delay completion of the restriction. The firm’s Idaho ignition-interlock guide explains installation, proof, restricted vehicles, and the current compliance rules without repeating them here.
An alcohol evaluation is generally part of sentencing
Idaho Code section 18-8005 generally requires a person who pleads guilty to or is found guilty of excessive DUI to obtain an alcohol evaluation before sentencing. For a first violation, the statute gives the court limited discretion to waive that evaluation when specified information or a qualifying recent assessment is already available. It is therefore inaccurate to say the evaluation can never be waived.
If an evaluation recommends treatment, the court ordinarily must order the recommended program or a comparable alternative unless the court finds on the record that treatment would be inappropriate or undesirable. Evaluation and treatment are sentencing subjects; they do not determine whether the state can prove the charge.
Testing issues in a 0.20 case
A result near the 0.20 threshold makes it especially important to identify exactly how the sample was collected, analyzed, approved, and reported. Depending on the test, relevant records can include:
- the complete breath-test printout, observation-period evidence, operator records, and instrument quality-control history;
- blood-draw authorization, collection records, tube information, chain of custody, laboratory notes, chromatograms, calibrations, and quality-control results;
- the times of driving, arrest, test request, sample collection, and analysis;
- body-camera, dash-camera, booking, and hospital video; and
- records of any additional test the driver requested under Idaho law.
The Idaho Supreme Court’s decision in State v. Jones rejected simply subtracting a laboratory measurement-of-uncertainty value to estimate a person’s “actual” alcohol concentration. The Court treated the properly administered test result—not an estimated physiological value—as controlling under the statutory per-se theory. That decision does not make every test immune from challenge. It distinguishes an uncertainty argument about the person’s actual concentration from evidence bearing on whether the testing equipment, method, sample, or procedure was reliable and legally compliant.
For test-specific issues, use the firm’s separate guides to Idaho DUI breath tests and Idaho DUI blood tests. The broader DUI defense guide covers stops, actual physical control, statements, and other case-wide issues.
Excessive DUI is not the same as aggravated DUI
“Excessive” describes the 0.20-or-higher alcohol-concentration enhancement. “Aggravated DUI” is a different felony statute tied to causing great bodily harm, permanent disability, or permanent disfigurement to another person. A serious-injury allegation can exist at a lower test result, and a 0.20 result does not by itself prove aggravated DUI.
Read the firm’s separate guide to aggravated DUI in Idaho for the injury and causation issues. General third-offense and prior-felony enhancements belong on the Idaho felony DUI page.
The first court appearance can happen quickly
Idaho Misdemeanor Criminal Rule 5(b) provides that a person arrested or cited for an enhanced DUI under section 18-8004C and then released must personally appear before a magistrate for arraignment within 48 hours, excluding Saturdays, Sundays, and holidays, subject to the rule’s medical postponement provision. Follow the citation and court instructions; do not assume an attorney appearance automatically excuses a required personal appearance.
The firm’s Ada County DUI court-process guide explains arraignment, discovery, motions, negotiation, trial, and sentencing without duplicating the penalty rules on this page.
Frequently asked questions
Is 0.20 exactly the threshold for excessive DUI in Idaho?
Yes. Section 18-8004C uses an alcohol concentration of 0.20 or more as shown by a police-requested analysis of blood, breath, or urine. The state must also prove the underlying DUI.
Is a 0.20-or-higher DUI automatically a felony?
No. When the current case is the person’s first DUI violation, section 18-8004C(1) makes the 0.20-or-higher offense a misdemeanor, although it carries mandatory jail, a fine of up to $2,000, and at least one year of absolute license suspension after release from confinement. The special excessive-DUI felony requires a qualifying prior 0.20-or-higher violation within five years; a lower-result prior may instead activate a general repeat-DUI provision.
Does any prior DUI make a new excessive DUI a felony?
No. The special felony provision requires a qualifying prior 0.20-or-higher violation within five years. A lower-result prior may trigger a different repeat-DUI enhancement.
Can I get a work permit during an excessive-DUI suspension?
There is no ordinary hardship permit during the statutory absolute suspension. A narrow exception may exist for a participant in good standing in an approved problem-solving court after at least 45 days and only if all statutory conditions are met.
Does the one-year license suspension start on the arrest date?
The criminal excessive-DUI statute says the court-ordered suspension runs after release from confinement. A separate ALS has its own service and effective dates. The actual orders and ITD status—not the arrest date alone—control.
Can measurement uncertainty automatically reduce a 0.20 result below the threshold?
No automatic subtraction rule applies. State v. Jones rejected using measurement uncertainty merely to estimate a lower “actual” concentration, while leaving case-specific equipment, method, sample, and procedural issues to be evaluated on their own facts.
Talk with an Idaho DUI defense attorney
An excessive-DUI case should be reviewed with the underlying DUI elements, test records, prior history, administrative deadline, and court suspension considered together. Contact Attorneys of Idaho for a confidential case review or call 208-314-8888.
This page provides general information, not legal advice for a particular case. Statutes, court rules, and procedures can change.
Talk With an Idaho DUI Defense Attorney
Deadlines and defense options depend on the facts of your case. Contact Attorneys of Idaho for a free, confidential case review.
