In Voigt v. Voigt, 22 Wis. 2d 573, 126 N.W.2d 543 (1964), the defendant was killed as the result of an accident when he crossed over into the plaintiff's lane of traffic. The supreme court held that the trial court erred in failing to deliver a res ipsa loquitur instruction, but that such error was harmless. See id. at 579-82. The defense contended that this represented an alternative nonnegligent explanation for the accident. See id. at 582. The court stated the issue as follows: "Upon whom does the duty rest to establish the ... nonnegligent nature of the invasion of the wrong lane of travel?" Id. at 583. The court concluded that the burden properly lies with the party who seeks to relieve himself or herself of the inference of negligence. See id. at 584. The court then said: "We do not hereby revise the rule that an injured plaintiff has the burden of proving that the defendant driver was negligent. However, once having introduced evidence that the defendant driver crossed into the wrong lane, the defendant driver has the burden of going forward with evidence to prove that such invasion was nonnegligent." Id. Upholding the jury's assessment of 90% negligence against the defendant, the court concluded that the evidence of the defendant's skidding did not relieve him of the burden of showing that he had exercised ordinary care. See id.