Idaho has a separate alcohol-concentration offense for drivers under 21. Under Idaho Code section 18-8004(1)(d), it is unlawful for a person under 21 with an alcohol concentration of at least 0.02 but less than 0.08 to drive or be in actual physical control of a motor vehicle.
This is not simply the ordinary adult DUI charge with a lower suggested guideline. It is a distinct misdemeanor with its own penalty statute, Idaho Code section 18-8004A. A result of 0.08 or higher can support the ordinary DUI provision, and a drug- or impairment-based DUI can involve different proof.
Idaho’s Under-21 Alcohol-Concentration Rule
| Driver and allegation | Potential Idaho provision |
|---|---|
| Under 21, alcohol concentration of at least 0.02 but less than 0.08 | Under-21 concentration offense under sections 18-8004(1)(d) and 18-8004A |
| Alcohol concentration of 0.08 or higher | Ordinary per se DUI provision under section 18-8004(1)(a), regardless of being under 21 |
| Driving under the influence of alcohol, drugs, another intoxicating substance, or a combination | Impairment-based DUI under section 18-8004(1)(a); a lawful prescription is not automatically a defense |
The under-21 offense applies to driving and to actual physical control. Idaho defines actual physical control as being in the driver’s position with the motor running or with the vehicle moving.
Does the State Have to Prove Impairment?
For the under-21 concentration offense, the State relies on the statutory alcohol concentration rather than needing to prove that the driver looked visibly impaired. The State must still prove the charged elements, including age, driving or actual physical control, and a qualifying test result.
A test number is evidence, not a substitute for reviewing how the stop, investigation, collection, analysis, and identification of the sample occurred. Depending on the case, relevant records may include body-camera video, breath-instrument data, operator records, blood-collection documents, chain of custody, laboratory material, and medical evidence.
Current Penalties Under Idaho Code Section 18-8004A
First Under-21 Concentration Offense
- A misdemeanor conviction;
- A fine of up to $1,000;
- A one-year court-ordered license suspension, with the first 90 days absolute and not reducible;
- Possible restricted driving privileges after the 90-day absolute period if the court finds the statutory showing has been made;
- A written advisement about consequences of a later DUI violation; and
- An alcohol evaluation and compliance with the applicable requirements as ordered by the court.
The first-offense subsection does not prescribe a mandatory jail term. It does impose a substantial one-year license suspension, and no driving privileges may be granted during its first 90 days.
Under-21 Offense After One Qualifying Prior
A prior can include a qualifying Idaho DUI under section 18-8004(1)(a), (b), (c), or (d), or a substantially conforming foreign violation. The statute says the prior can count notwithstanding the form of the judgment or a withheld judgment.
- A mandatory jail term of at least five days and no more than 30 days;
- A fine from $500 to $2,000;
- A court-ordered license suspension of up to two years, with the first year absolute and not reducible;
- An ignition-interlock restriction under section 18-8008 after the mandatory one-year suspension period;
- A written advisement about later violations; and
- An alcohol evaluation and the other applicable requirements.
Under-21 Offense With Two or More Qualifying Priors Within Five Years
- A mandatory jail term of at least 10 days and no more than six months;
- A fine from $1,000 to $2,000;
- Surrender of the driver’s license or permit;
- An absolute suspension for at least one year or until the person reaches age 21, whichever is greater;
- An ignition-interlock restriction under section 18-8008 after the mandatory one-year suspension period; and
- An alcohol evaluation and the other court-imposed requirements.
These are statutory ranges and requirements, not a prediction of the result in an individual case. The broader Idaho DUI penalties guide explains how the under-21 provision differs from ordinary, excessive, and felony DUI.
The License Case Can Start Before a Conviction
The court suspension described above is a consequence of conviction. A separate driver’s-license proceeding may begin immediately after the arrest:
- A failed evidentiary test may lead to an administrative license suspension through ITD. A written hearing request must be received by ITD within seven calendar days after service of the suspension notice.
- An alleged refusal or failure to complete evidentiary testing is handled through the separate implied-consent refusal process. A hearing request goes to the court within seven days from the refusal.
The criminal case, failed-test ALS, and refusal proceeding are not interchangeable. A favorable outcome in one does not automatically resolve another.
Restricted Driving and Ignition Interlock
After a first conviction under section 18-8004A, the first 90 days of the one-year court suspension are absolute. After that period, the driver may ask the court for restricted privileges and must prove that driving is necessary as deemed appropriate by the court. A permit is not automatic.
Repeat-offense provisions contain longer absolute periods and ignition-interlock requirements. Review the exact judgment and ITD record before driving. Our guides explain Idaho restricted driving permits, ignition-interlock requirements, and SR-22 and license reinstatement.
How an Underage DUI Case May Be Reviewed
No single defense applies to every case. A case-specific review may examine:
- whether the officer had a lawful basis for the stop and any extension of the detention;
- whether the State can prove the driver’s age and identity;
- whether the State can prove driving or actual physical control;
- whether the result falls within the specific concentration range charged;
- the timing, collection, preservation, and analysis of breath, blood, or urine evidence;
- instrument, operator, laboratory, and chain-of-custody records;
- whether medical facts or other evidence provide context for the officer’s observations; and
- whether an alleged prior conviction legally qualifies for an enhanced tier.
A deviation from a recommended procedure does not automatically dismiss the case. Its effect depends on the governing rule, the available foundation, and whether it affects admissibility, weight, or reliability. Learn more in the guides to field sobriety tests, breath-test evidence, and blood-test evidence.
What to Do After an Underage DUI Arrest
- Keep and copy every citation, notice, temporary permit, release order, and court document.
- Identify whether the paperwork alleges a failed test or refusal and act on the correct seven-day deadline.
- Do not drive unless current privileges are verified and every restriction is satisfied.
- Preserve receipts, location history, relevant messages, video, witness information, and medical or prescription records without altering them.
- Follow all release conditions and attend every required court or supervision appointment.
- If the driver needs medical or substance-use help, obtain appropriate care; for court credit, verify that an evaluator or program satisfies Idaho requirements.
- Have the criminal charge and any separate license proceeding reviewed together.
Section 18-8004A also permits prosecution under Idaho’s juvenile-law title, so the forum and procedure may depend on the driver’s age and the charge. The Ada County DUI court-process guide explains the ordinary adult criminal stages, while the individual charging documents identify the actual court.
Frequently Asked Questions
Is Idaho’s under-21 limit zero?
The specific driving offense begins at an alcohol concentration of 0.02 and applies below 0.08. Separate alcohol-possession or consumption laws may also apply, but they are not the same charge.
What happens at 0.08 or higher?
A driver under 21 can be prosecuted under the ordinary 0.08 per se DUI provision. The under-21 concentration offense is specifically written for results of at least 0.02 but less than 0.08.
Can a withheld judgment still count as a prior?
Yes. Section 18-8004A expressly says qualifying prior violations can count notwithstanding a withheld judgment. Our Idaho withheld-judgment guide explains why dismissal after a withheld judgment does not make every statutory consequence disappear.
Can a first-offense driver request restricted privileges?
After the 90-day absolute portion of the one-year court suspension, the driver may request restricted privileges. The court may grant them only after the required showing; eligibility is not automatic.
Does a lawful prescription prevent a drug-DUI charge?
No. Idaho Code section 18-8004 states that entitlement to use a drug is not itself a defense to a DUI allegation involving that drug. The State still must prove the charged DUI elements. See the guide to drug DUI in Idaho.
Where can a family review the related Idaho DUI issues?
The Idaho DUI Help Center organizes the firm’s resources on testing, license proceedings, charges, court procedure, and special situations.
Get the Charge and License Notices Reviewed
An under-21 case can involve a criminal charge, an immediate license deadline, and consequences that affect school, work, and transportation. Contact Attorneys of Idaho for a review of the citation, test allegation, and driver’s-license paperwork.
This page provides general information, not legal or medical advice for a particular case. Statutes, forms, procedures, and agency requirements can change.