## Facts

- Gary Caibaiosai operated a 1977 Harley-Davidson motorcycle on Highway 142 in Wisconsin with passenger Janet M. Tunkieicz.
- Witness testimony indicated Caibaiosai passed another motorcycle by entering the oncoming lane and was traveling about 60–65 mph; other testimony about additional motorcycles was conflicting.
- Caibaiosai crashed; Tunkieicz died at the scene and Caibaiosai survived.
- About two hours after the crash, Caibaiosai’s blood-alcohol concentration measured 0.13%.
- The State charged Caibaiosai with homicide by intoxicated use of a motor vehicle under Wis. Stat. § 940.09(1)(a).
- The jury was instructed that the State had to prove Caibaiosai’s operation of the motorcycle was a substantial factor in causing death, and that it was not required to prove alcohol consumption or negligent driving caused the death.
- Caibaiosai was convicted; postconviction he sought a new trial, arguing the statute was unconstitutional and that he was entitled to an instruction on the statutory affirmative defense in § 940.09(2).

## Issues

1. Whether Wis. Stat. § 940.09(1)(a) is unconstitutional because it does not require proof that the defendant’s intoxication caused the death.
2. Whether Wis. Stat. § 940.09(2), which allows an affirmative defense but places its burden on the defendant, violates the Fifth Amendment privilege against self-incrimination.
3. Whether refusing to instruct the jury on the § 940.09(2) affirmative defense denied due process and a fair trial.

## Decision

- The Wisconsin Supreme Court affirmed the conviction.
- The court held § 940.09(1)(a) constitutional even though it does not require proof that intoxication caused the death; it is sufficient that the defendant, while under the influence, operated the vehicle and that operation was a substantial factor in causing death.
- The court held § 940.09(2)’s affirmative defense and burden allocation did not violate the Fifth Amendment.
- The court held the trial court properly refused the affirmative-defense instruction because the record lacked evidence that the death would have occurred even if Caibaiosai had not been intoxicated.

## Legal Principles

- A legislature may define homicide by intoxicated use of a vehicle to require causation by the defendant’s operation of the vehicle (as a substantial factor in the death) without requiring a further causal link between intoxication and the death.
- Such a statute satisfies constitutional review if it bears a rational relationship to legitimate governmental objectives, including deterrence of intoxicated driving and public safety.
- Placing on a defendant the burden to prove an affirmative defense by a preponderance of the evidence does not, by itself, compel self-incrimination or violate the Fifth Amendment.
- A defendant is entitled to a requested jury instruction on a defense theory only when there is some evidentiary basis for it; a trial court may refuse instructions unsupported by the evidence.

## Conclusion

Wisconsin upheld a vehicular-homicide-by-intoxication statute that does not require the State to prove intoxication caused the death, approved an affirmative defense placing a preponderance burden on the defendant, and found no error in refusing the defense instruction where the evidence did not support it.


State v. Caibaiosai, 363 N.W.2d 574 (Wis. 1985)