DUI Laws in Idaho: Penalties, BAC Limits & License Suspension

In Idaho, drunk or drugged driving is charged as Driving Under the Influence (DUI) under Idaho Code § 18-8004 — the state does not use "DWI" or "OWI." The per se limit is 0.08% BAC for standard drivers (0.04% for commercial license holders, 0.02% for drivers under 21). If you were arrested and handed a suspension notice, the clock is already running: you typically have only seven calendar days to request a hearing with the Idaho Transportation Department (ITD) to fight the automatic suspension of your license — miss it, and the suspension takes effect on its own. Read the rest of this guide, but request that hearing first.

What a DUI Is Called in Idaho

Idaho law refers to the offense simply as DUI — Driving Under the Influence, codified at Idaho Code § 18-8004. It covers driving or being in "actual physical control" of a vehicle while impaired by alcohol, drugs, or a combination, or while at or above the applicable blood-alcohol concentration (BAC) threshold for your driver category. There is no separate "DWI" or "OWI" charge — everything runs through the DUI statutes in Title 18, Chapter 80 of the Idaho Code.

Idaho's BAC Limits

Idaho sets different per se thresholds depending on who is driving:

• 0.08% BAC — the standard per se limit for drivers 21 and older, the same baseline used nationwide.
• 0.04% BAC — the limit for holders of a commercial driver's license (CDL) operating a commercial motor vehicle.
• 0.02% BAC — Idaho's under-21 threshold. A driver under 21 with a BAC of at least 0.02 but under 0.08 can be cited under Idaho's separate minor-DUI provision (Idaho Code § 18-8004A), even though that's below the adult per se limit.
• 0.20% BAC — "excessive DUI" — Idaho Code § 18-8004C creates an enhanced-penalty tier for anyone who tests at 0.20% or higher. This threshold is notably higher than the 0.15% "high-BAC" line used in many other states, so don't assume Idaho's aggravated cutoff matches what you may have read about elsewhere.

These numbers can be amended by the legislature, so confirm the current figures against Idaho Code § 18-8004, § 18-8004A, and § 18-8004C before relying on them.

Implied Consent and Refusing a Test

By driving in Idaho, you've already agreed — under Idaho Code § 18-8002 — to submit to an evidentiary test (breath, blood, or urine) if an officer has reasonable grounds to believe you were driving under the influence. Refusing that test doesn't avoid consequences; it triggers its own separate, automatic license suspension, independent of any DUI charge:

• First refusal: a one-year absolute suspension (commonly reported with no restricted/work-permit driving available during that period), plus a civil penalty and a period of required ignition-interlock use once driving privileges resume.
• Second refusal within 10 years: a longer suspension, commonly cited at two years.

Just as important: prosecutors can also use your refusal as evidence against you at trial. Refusing does not make a DUI case disappear — it adds a suspension on top of whatever happens with the underlying charge. You generally have the same short window (about seven days) to request a hearing contesting a refusal-based suspension as you do for a test-failure suspension — see below. Confirm the exact current suspension lengths with Idaho Code § 18-8002 or the Idaho Transportation Department, since refusal penalties are amended periodically.

The Administrative License Suspension (ALS) — Your Deadline Is Short

Separate from any criminal DUI case, Idaho runs a civil license-suspension process through the Idaho Transportation Department (ITD). If you tested at or above the per se limit, or refused testing, the arresting officer serves you with a Notice of Suspension on the spot. That notice starts a clock:

• You generally have only seven (7) calendar days from the date of service to submit a written request for an administrative hearing to contest the suspension.
• If you don't request a hearing in time, the right to contest the suspension is waived and it takes effect — with no further chance to challenge it administratively.
• A hearing, once properly requested, is limited to specific issues: whether the officer had grounds for the stop, whether the arrest was lawful, whether you were properly advised of implied consent, and whether the test itself was reliable.

This is the single most time-sensitive piece of a DUI arrest in Idaho. Confirm the current deadline and submission method directly with ITD's driver services division, since a missed filing window cannot be undone after the fact.

First-Offense Penalties

For a standard first-offense DUI conviction, Idaho law authorizes a range of penalties rather than a single fixed sentence. Reported figures include:

• Jail: up to roughly six months, with the actual sentence (if any beyond fines/probation) left largely to the court's discretion for a first offense.
• Fine: up to roughly $1,000, before court costs and fees, which can add substantially to the total.
• License suspension: commonly reported as a total suspension period in the range of 90 to 180 days, with an initial "hard" or absolute portion (no driving at all) followed by potential eligibility for a restricted/work permit for the remainder — sometimes conditioned on installing an ignition interlock device (IID).
• Ignition interlock device (IID): not automatically required for every standard first offense the way it is for repeat offenses or an excessive-DUI (0.20%+) conviction, but courts frequently require an IID as a condition of granting any restricted driving privileges during the suspension.

Because exact jail, fine, and suspension figures are subject to legislative change and can vary with the specifics of your case, treat the ranges above as a general pattern rather than a guarantee, and confirm the current statute — Idaho Code §§ 18-8004 and 18-8005 — or check with the court or a local defense attorney for the numbers that apply to your case today.

Lookback (Washout) Period: 10 Years

Idaho counts a prior DUI as an enhancing "prior" if it falls within 10 years of the current offense, measured from the date of the earlier guilty plea or finding of guilt (not the arrest date). Out-of-state DUI convictions generally count too, if the other state's law is substantially similar to Idaho's. A DUI conviction (or withheld judgment) older than 10 years generally will not enhance a new charge, but it can still be brought up in other contexts, such as sentencing discretion.

When a DUI Becomes a Felony

A DUI in Idaho is elevated from a misdemeanor to a felony when:

• It is a person's third (or subsequent) DUI conviction within the 10-year lookback period (two or more prior qualifying convictions, including certain withheld judgments and diversions, count toward this).
• It is a second "excessive DUI" (0.20%+ BAC) within five years of a prior excessive-DUI conviction, under Idaho's separate high-BAC enhancement.
• The DUI involves serious injury or death, which can be charged as separate, more serious felony offenses (such as vehicular manslaughter or aggravated DUI causing injury) carrying substantially longer potential prison exposure than a standard misdemeanor DUI.

Felony DUI carries state prison exposure measured in years rather than months, along with fines and license consequences well beyond the misdemeanor tiers described above. If any of these factors might apply to your situation, the stakes are high enough that confirming the specifics with a local defense attorney is worth the time.

What to Do After a DUI Arrest in Idaho

1. Read every paper the officer gave you the moment you can. Find the Notice of Suspension and note the date of service — that date starts your short hearing-request window.
2. Request an ALS hearing in writing within the deadline (about 7 days). Do not wait to "figure things out" first — contact the Idaho Transportation Department's driver services division immediately to confirm the correct mailing/submission method and current deadline, since missing it locks in the suspension automatically.
3. Note your court dates. The criminal DUI case and the civil ALS suspension are two separate tracks that proceed on their own timelines — handling one does not resolve the other.
4. Ask about temporary/restricted driving privileges. Depending on the suspension type and stage, a restricted permit (often requiring an ignition interlock) may become available after part of the suspension period.
5. Preserve your own memory of events — write down what you remember about the stop, the tests, and the arrest while it's fresh, including times and any statements made.
6. Talk with a licensed Idaho criminal defense attorney as soon as possible, particularly if this is not a first offense, if BAC was reported at 0.20% or higher, or if anyone was injured — these facts can move the case toward felony exposure.

This article is general legal information about Idaho law, not legal advice for your specific situation — confirm current statutes and deadlines with the Idaho Transportation Department, the Idaho courts, or a licensed Idaho attorney.