Idaho DUI Laws

The per se limit is 0.08% (Idaho Code § 18-8004(1)(a)). The offense also covers impairment by drugs or other intoxicating substances without a specific BAC. The CMV threshold is 0.04% (§ 18-8004(1)(b)). The under-21 threshold is 0.02% (§ 18-8004(1)(d)).

A first offense is a misdemeanor: up to 6 months in jail, up to $1,000 fine, a 30-day absolute license suspension followed by 60–150 days of additional suspension, and IID for 1 year after the suspension (Idaho Code § 18-8005(1)).

A second offense within 10 years is a misdemeanor: 10-day mandatory minimum to 1 year in jail, up to $2,000 fine, a 1-year mandatory absolute license suspension, and IID after the suspension (Idaho Code § 18-8005(4)).

Three ways. (1) A third or subsequent offense with 2+ priors within 10 years is a felony carrying up to 10 years in the penitentiary (Idaho Code § 18-8005(6)). (2) Any person with a prior felony DUI who commits a further DUI within 15 years is automatically a felony regardless of the 10-year counter (§ 18-8005(9)). (3) A SECOND "excessive DUI" (BAC 0.20% or more) within 5 years of a prior 0.20%+ offense is a felony under § 18-8004C(2) — up to 5 years and a $5,000 fine — so an excessive-DUI defendant can be a felon on a second offense, without needing three offenses.

Yes — IID is mandatory at every tier (Idaho Code § 18-8005(1)(e), (4)(f), (6)(e)). First offense: 1 year after the suspension. Second and third+: IID after the mandatory 1-year absolute suspension. A court may waive on exceptional circumstances, but financial hardship alone is insufficient (§ 18-8002(12)).

Refusing an evidentiary test carries a civil (not criminal) penalty: $250, a 1-year absolute license suspension (2 years for a second refusal within 10 years), and mandatory IID for 1 year following the suspension (Idaho Code § 18-8002(4)). The sanction runs separately from any criminal conviction. No right to consult an attorney before testing (§ 18-8002(2)).

A driver under 21 with a BAC of 0.02 or more but less than 0.08 commits a misdemeanor under Idaho Code § 18-8004(1)(d), penalized under § 18-8004A. A first offense carries up to $1,000 and a 1-year license suspension (90 days absolute). A second offense within 5 years carries a 5-day mandatory minimum (up to 30 days), a $500–$2,000 fine, and up to a 2-year suspension (1 year absolute) with IID after (§ 18-8004A(2)). A third or subsequent offense within 5 years carries a 10-day mandatory minimum (up to 6 months), a $1,000–$2,000 fine, and a 1-year absolute suspension — or until age 21, whichever is longer — with IID after (§ 18-8004A(3)). A driver under 21 at 0.08+ is charged under the adult § 18-8004(1)(a).

A 10-year window governs the misdemeanor-to-felony escalation (§ 18-8005(4)/(6)). A separate 15-year overlay provides that any person with a prior felony DUI who commits a further DUI within 15 years is automatically charged as a felony (§ 18-8005(9)). Prior qualifying offenses include Idaho DUI, substantially conforming out-of-state/federal violations, and DUI-diversion-program completions.

A first offense brings a 30-day absolute suspension followed by 60–150 days of additional suspension (restricted driving possible). A second offense within 10 years brings a 1-year mandatory absolute suspension. A felony third+ brings a 1-year mandatory absolute suspension (up to 5 years total). IID is required after every suspension period. A separate 1-year (or 2-year) absolute suspension applies on refusal.