IID mandatory for all repeat offenders and for any first offense at 0.15+ or with a refusal (1 year+); occupational licenses require IID where applicable.
By offense
First offense: IID not required at this level — IID mandatory 1 year if BAC 0.15+ (or on refusal); otherwise not required on a bare first offense.
Second offense: IID required
Third offense: IID required
Fourth+ offense: IID required
Statute: Wis. Stat. § 343.301
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