Idaho DUI Laws: Offenses, Penalties, and License Suspension

Idaho DUI laws make it a crime to drive, or to be in actual physical control of a vehicle, while impaired by alcohol, drugs, or any other intoxicating substance. A first offense is a misdemeanor; a third within ten years is a felony. Standard drivers hit the legal limit at a blood alcohol concentration of 0.08%, commercial drivers at 0.04%, and drivers under 21 at 0.02%. A conviction brings jail time, fines, a court-ordered license suspension, and a separate administrative suspension handled by the Idaho Transportation Department that you have only seven days to challenge.

What Counts as DUI in Idaho

You don’t have to be moving. Idaho Code 18-8004 reaches anyone in “actual physical control” of a vehicle while impaired, so sitting in the driver’s seat with the engine running can be enough for a charge.¹

The BAC thresholds break out by driver type:

0.08% or higher for drivers 21 and over
0.04% or higher for commercial motor vehicle operators
0.02% or higher for drivers under 21, under Idaho’s zero-tolerance rule

BAC is measured through blood, breath, or urine testing requested by a law enforcement officer.¹

Impairment from prescription medications, over-the-counter drugs, and illegal substances also qualifies. There is no per se chemical threshold for most drugs; if a substance diminishes your ability to drive safely, you can be charged based on observed impairment, often supported by standardized field sobriety tests.

Implied Consent and What Happens If You Refuse

By driving on Idaho roads, you’ve already consented to evidentiary testing if an officer has reasonable grounds to believe you’re impaired. You have no right to speak with an attorney before deciding whether to submit.²

Refusing carries its own penalties, separate from any DUI conviction. A first refusal brings a $250 civil penalty, a one-year license suspension with no restricted privileges, and mandatory ignition interlock installation at your expense on every vehicle you operate. A second refusal within ten years suspends your license for two years. You have seven days from the refusal to request a hearing. Miss that window and the suspension stands.²

After the officer’s test, you can arrange your own independent testing at your expense, which can matter later if you challenge the state’s results.

Penalties for a First DUI

A first DUI is a misdemeanor. There’s no mandatory minimum jail sentence, though a judge can impose up to six months. Fines can reach $1,000.³

License suspension runs in two stages. The court imposes 30 days of absolute suspension, meaning no driving of any kind, followed by another 60 to 150 days during which you can request restricted privileges for work or family health needs. Total suspension: 90 to 180 days. Courts routinely order an alcohol evaluation and any recommended treatment as a condition of sentencing.³

Penalties for a Second DUI

A second DUI within ten years remains a misdemeanor, but the numbers climb. Ten days minimum in jail (with the first 48 hours consecutive), up to one year, and fines up to $2,000.³

License suspension is a full year after release from confinement, with no driving privileges at all during that year. Once the year ends, you must install an ignition interlock on every vehicle you operate before driving again.³

Penalties for a Third or Subsequent DUI

A third DUI within ten years is a felony. The maximum jumps to ten years in state prison. If the court chooses not to impose a prison term, the mandatory minimum is 30 days in county jail with the first 48 hours consecutive. Fines can reach $5,000.³

Driving privileges are suspended for a mandatory year after release, with no driving during that period. The court can add up to four more years of suspension, during which restricted privileges are possible. An ignition interlock is required on every vehicle you operate once the one-year absolute period ends.³

Excessive BAC and DUI Causing Injury

Two situations escalate a case outside the ordinary progression. When BAC hits 0.20% or higher, Idaho applies enhanced penalties. A first excessive-BAC offense is still a misdemeanor but carries a ten-day minimum in jail (48 hours consecutive), up to a year, fines up to $2,000, and a full year of license suspension after release with no driving. A second excessive-BAC offense within five years is a felony punishable by up to five years in prison and fines up to $5,000. Note the five-year lookback here, shorter than the ten-year window for standard repeat offenses.⁴

Causing great bodily harm, permanent disability, or permanent disfigurement to another person while impaired is a standalone felony no matter your prior record. Maximum sentence: 15 years. If the court doesn’t impose prison, the mandatory minimum is 30 days in county jail with the first 48 hours consecutive. Fines can reach $5,000, license suspension runs one to five years after release, and the court must order restitution to the victim for medical costs, lost income, and other damages. Driving impaired with a minor in the car can produce a separate child endangerment charge on top of the DUI.⁵

Administrative License Suspension: The Seven-Day Deadline

The Idaho Transportation Department runs its own license suspension on a separate track from the criminal case. It can suspend your license based on the test result alone, even if the criminal charges are later reduced or dismissed.

Failing a test brings a 90-day suspension for a first failure. The first 30 days are absolute; you can request restricted noncommercial privileges for the remaining 60. A second failure within five years brings a full year with no restricted privileges available.⁶

Refusing brings a one-year suspension for a first refusal and two years for a second within ten years, with no restricted license available either way. Both scenarios also require ignition interlock installation on every vehicle you operate, at your expense, for one year after the suspension ends.⁶

You have seven days from the notice of suspension to request an administrative hearing. Miss the deadline and the suspension is final. Win the hearing and the administrative suspension is vacated, though the criminal case continues on its own.⁶

What a DUI Actually Costs

The court fine is usually the smallest line item. To get your license back after an Idaho DUI conviction, the reinstatement fee is $285. Out-of-state DUI convictions, refusals, and administrative suspensions carry a $245 reinstatement fee.⁷

Anyone convicted of DUI in Idaho must file an SR-22, a certificate of financial responsibility that your insurer files with the state on your behalf, and maintain it for three years. Premiums commonly double or triple, and some insurers cancel coverage entirely, forcing a switch to a high-risk carrier.⁷

Ignition interlock devices typically cost $70 to $150 to install plus a monthly monitoring fee, and the requirement often runs well over a year. Court-ordered alcohol evaluations run $100 to $350, with treatment on top of that. Private defense counsel for a first-offense case generally runs $1,500 to $10,000 depending on complexity and whether the case goes to trial. None of these expenses are tax-deductible.

Consequences a DUI Conviction Can Reach Into

A felony DUI (third within ten years, excessive-BAC second within five years, or DUI causing injury) suspends your civil rights while you’re incarcerated, including voting, jury service, and holding public office. Idaho restores most civil rights automatically upon final discharge, which means completion of the full sentence including probation or parole. Firearm rights follow a similar path for a standard felony DUI, though enumerated offenses carry longer or permanent bars. Felony convictions also show up on background checks and can affect professional licensing in fields like healthcare, education, and law.

International travel is a frequent surprise. Canadian immigration law treats impaired driving as a serious crime, and a single U.S. misdemeanor DUI can render you inadmissible. Canadian border officers can access U.S. criminal databases at airports, land crossings, and seaports. You may qualify for “deemed rehabilitation” once enough time has passed, or you can apply for individual rehabilitation once at least five years have elapsed since the end of your entire sentence. A Temporary Resident Permit can cover urgent travel while you remain inadmissible.⁸

How DUI Charges Get Challenged

Most Idaho DUI defenses start with the stop. An officer needs reasonable suspicion of a traffic violation or criminal activity to pull you over. If the stop rested on a hunch rather than observable facts, evidence gathered afterward may be suppressed.

BAC testing is a second common target. Breathalyzers require regular calibration, operators must be certified, and officers must follow protocols including a 15-minute observation period before the test. Failures on any of those can make the result unreliable. Idaho law allows the prosecution to proceed on other evidence when the BAC result is thrown out, but the case is much harder to prove without a number.¹

Field sobriety tests are subjective. Uneven pavement, poor lighting, medical conditions, nervousness, and footwear can all affect performance, and an officer’s interpretation of “clues” is opinion rather than measurement. For drug-related charges without a BAC reading, the prosecution leans on officer observations and sometimes a drug recognition expert, and those cases are more vulnerable to challenge because Idaho generally has no per se impairment threshold for drugs.

1
Idaho State Legislature. Idaho Code 18-8004 – Persons Under the Influence of Alcohol, Drugs or Any Other Intoxicating Substances
2
Idaho State Legislature. Idaho Code 18-8002 – Tests of Driver for Alcohol Concentration, Presence of Drugs or Other Intoxicating Substances – Penalty and Suspension Upon Refusal of Tests
3
Idaho State Legislature. Idaho Code 18-8005 – Penalties
4
Idaho State Legislature. Idaho Code 18-8004C – Excessive Alcohol Concentration
5
Idaho State Legislature. Idaho Code 18-8006 – Persons Under the Influence of Alcohol, Drugs or Any Other Intoxicating Substances Penalties for Injury
6
Idaho State Legislature. Idaho Code 18-8002A – Tests of Driver for Alcohol Concentration, Presence of Drugs or Other Intoxicating Substances
7
Idaho Transportation Department. SR-22 and Reinstatement Information
8
Government of Canada. Overcome Criminal Convictions