Vehicular manslaughter in Idaho is a criminal charge brought when a driver’s operation of a motor vehicle is a significant contributing cause of another person’s death. Idaho Code 18-4006 splits the offense into three tiers: a misdemeanor for a fatal crash caused by an ordinary unlawful act, a felony when gross negligence is involved, and a felony when the driver was under the influence. Penalties run from up to one year in county jail to as much as 25 years in state prison, with the DUI tier carrying mandatory minimum prison terms when the driver has prior DUI convictions.1Idaho State Legislature. Idaho Code 18-4006 – Manslaughter Defined
The Three Categories Under Idaho Code 18-4006
Idaho does not have a single vehicular manslaughter charge. Section 18-4006(3) creates three separate offenses, and every one of them requires the state to prove that the defendant’s driving was a significant cause contributing to the death. What distinguishes them is the kind of misconduct behind the wheel.
Subsection (c), the misdemeanor, applies when the driver committed an unlawful act that is not a felony and did so without gross negligence. Rolling a stop sign, drifting out of a lane, or slightly exceeding the speed limit can all qualify if the violation directly contributed to a fatal collision. The driver broke a traffic law, but the error was the kind most people would recognize as careless rather than reckless.1Idaho State Legislature. Idaho Code 18-4006 – Manslaughter Defined
Subsection (a), the gross-negligence felony, applies when the unlawful act involved conduct so far outside the bounds of reasonable driving that it amounts to a conscious disregard for danger. Blowing through a school zone at highway speed or weaving aggressively through heavy traffic at extreme speed is the kind of behavior that supports this charge. Prosecutors weigh the full picture: speed, traffic, visibility, whether passengers were present, and whether the driver had reason to know the behavior was dangerous. The line between ordinary and gross negligence is ultimately a jury question.
Subsection (b), the DUI felony, applies when the driver violated Idaho’s DUI statute (Section 18-8004) or aggravated DUI statute (Section 18-8006) and the impaired driving significantly contributed to the death. Idaho defines DUI as driving with a blood alcohol concentration of 0.08 or higher, or driving while under the influence of alcohol, drugs, or any other intoxicating substance. The threshold drops to 0.04 for commercial drivers and 0.02 for drivers under 21.2Idaho State Legislature. Idaho Code 18-8004 – Persons Under the Influence of Alcohol, Drugs or Any Other Intoxicating Substances The state does not have to prove gross negligence in a DUI case; it has to prove impairment and causation.
The aggravated DUI statute at 18-8006 specifically covers impaired drivers who cause great bodily harm, permanent disability, or permanent disfigurement.3Idaho State Legislature. Idaho Code 18-8006 – Aggravated Driving Under the Influence When the victim dies, prosecutors charge vehicular manslaughter under 18-4006(3)(b) instead.
Penalties by Category
The sentencing ladder in Idaho Code 18-4007 tracks the three subsections of the manslaughter statute.
A misdemeanor conviction under subsection (c) carries up to one year in county jail, a fine of up to $2,000, or both.4Idaho State Legislature. Idaho Code 18-4007 – Punishment for Manslaughter Even this lowest tier leaves a permanent criminal record and triggers license revocation, which puts it well above a routine traffic offense.
A gross-negligence felony conviction under subsection (a) carries up to 10 years in the custody of the state board of correction, a fine of up to $10,000, or both.4Idaho State Legislature. Idaho Code 18-4007 – Punishment for Manslaughter
DUI vehicular manslaughter under subsection (b) is where Idaho’s sentencing gets especially harsh, because penalties escalate sharply with prior DUI history:
- No prior DUI convictions: up to 15 years in prison and a fine of up to $15,000, or both.
- One prior DUI conviction: a mandatory minimum of 5 years in prison as a fixed term, up to 25 years total, and a fine of up to $20,000.
- Two or more prior DUI convictions: a mandatory minimum of 10 years in prison as a fixed term, up to 25 years total, and a fine of up to $20,000.
Those mandatory minimums are fixed terms. A judge cannot suspend them or substitute probation.4Idaho State Legislature. Idaho Code 18-4007 – Punishment for Manslaughter A driver with two prior DUIs who kills someone in another impaired crash faces at least 10 years locked in, regardless of other circumstances. Prior out-of-state convictions count if they are substantially conforming to Idaho’s DUI law.
Courts can also order restitution to the victim’s family. In practice that typically covers funeral costs, medical expenses incurred before death, counseling for surviving family members, and lost financial support the victim would have provided.
Driver’s License Revocation and Reinstatement
Any vehicular manslaughter conviction triggers mandatory license revocation by the Idaho Transportation Department under Idaho Code 49-325. This administrative action runs separately from the criminal sentence.5Idaho State Legislature. Idaho Code 49-325 – Mandatory Revocation of License by Department
Vehicular manslaughter is not on the list of offenses eligible for a restricted driving permit, so a convicted driver generally cannot get limited privileges for work or other essential needs during the revocation period. Once the revocation period set by the court or department has run, the driver must apply for reinstatement and pay a $285 fee per vehicular manslaughter suspension.6Idaho Transportation Department. Driver License Reinstatement Form If the driver has multiple suspensions under Title 18, each one requires its own fee, and the fee is nonrefundable.
When Prosecutors Charge Second-Degree Murder Instead
In extreme cases Idaho prosecutors can bypass the manslaughter statute entirely and charge second-degree murder. The dividing line is malice. Vehicular manslaughter applies when there was no intent to kill. Second-degree murder applies when the driver’s conduct was so extreme that it shows an abandoned and malicious heart, which the law treats as equivalent to intentional killing.
This usually arises when a driver with multiple prior DUIs kills someone while impaired again, or when a driver flees police at extreme speeds through populated areas. The facts have to be extraordinary, but it does happen, and a second-degree murder conviction in Idaho carries up to life in prison. The vehicular manslaughter penalties above are the floor, not the ceiling, of what the state can pursue.
Common Defenses
Vehicular manslaughter cases are not automatic convictions. The prosecution still has to prove every element of the specific subsection charged, and several defenses show up repeatedly.
Causation. The state must prove that the driver’s operation of the vehicle was a significant cause contributing to the death. If the victim had a pre-existing medical condition, was jaywalking, or was at fault in a way that broke the causal chain, the defense can argue the driving was not a significant contributing cause. Cases often turn on this question.
Disputing gross negligence. In felony cases under subsection (a), the defense may argue that the driver’s conduct, while negligent, did not rise to gross negligence. A successful argument can reduce the charge to the misdemeanor under subsection (c), with a dramatic reduction in exposure.
Challenging impairment evidence. In DUI cases under subsection (b), defense attorneys often challenge the reliability of breath or blood tests, the calibration of testing equipment, the chain of custody for blood samples, or the legality of the traffic stop. If impairment evidence is suppressed, the state may not be able to sustain the DUI-based charge.
No unlawful act. All three subsections require either an unlawful act or a DUI violation. If the driver was obeying all traffic laws and the death resulted from an unavoidable event such as a tire blowout, a sudden medical event, or an unforeseeable road hazard, the defense can argue that no unlawful act occurred at all.
Voluntary intoxication is not a defense. A driver who chose to drink or use drugs cannot argue that impairment prevented them from forming the intent to drive dangerously.
Civil Wrongful Death Exposure
Criminal charges are only part of the picture. The victim’s family can also file a civil wrongful death lawsuit, and a criminal acquittal does not block it. Civil cases use a lower standard of proof, preponderance of the evidence rather than beyond a reasonable doubt, so a driver cleared criminally can still be found liable in civil court.
Idaho Code 5-311 lets the decedent’s heirs or personal representative bring the action and recover damages “as under all the circumstances of the case as may be just,” which gives courts wide latitude to award compensation for lost income, funeral costs, loss of companionship, and similar harms.7Idaho State Legislature. Idaho Code 5-311 – Wrongful Death Actions The statute of limitations is two years from the date of death.8Idaho State Legislature. Idaho Code 5-219 – Actions Against Officers, for Penalties, on Bonds and for Professional Malpractice or for Personal Injuries Missing that deadline almost always ends the claim.