Washington Supreme Court considers scope of "sudden incapacitation" defense in crash case

The Washington State Supreme Court heard argument June 16 in Aaron Brandt et al v. James Shaw over whether the state's "sudden incapacitation" affirmative defense should be evaluated under ordinary evidentiary rules at the summary-judgment stage or subjected to heightened requirements not in the Restatement or court rules.

Luke O'Bannon, counsel for the petitioner, told the court the defense is an affirmative one the defendant must prove at trial but argued that where medical evidence shows a stroke contemporaneous with a collision, the defense can bar a negligence claim without extra corroboration at summary judgment. "This case concerns the proper scope of Washington's sudden incapacitation defense and the evidentiary standards that apply at summary judgment," O'Bannon said, urging the court to reinstate the trial-court grant of summary judgment in favor of the defense.

Why it matters: The court's approach will affect when juries consider claims that drivers were incapacitated by medical events and whether plaintiffs can avoid summary judgment by relying on gaps in a defendant's memory. The decision could also affect how courts treat medical risk evidence, doctors' advice and routine clinical history in negligence suits.

A string of justices pressed both sides on timing and proof. "Is it an absolute bar to the plaintiff's case if this affirmative defense is established?" a justice asked, probing whether the defense should automatically negate ordinary negligence claims. O'Bannon responded the defense is a complete bar when the evidence shows the defendant was not otherwise engaging in an unsafe activity but acknowledged that competing negligence theories could preserve liability in some fact patterns.

Opposing counsel Matthew (Matt) Albrecht, representing the plaintiffs, framed the facts differently. "The case starts with an innocent driver who was stopped safely following all the rules and gets crashed into," Albrecht said, arguing the record contains no testimony that the stroke rendered the driver unable to control the vehicle or that the stroke preceded the impact. He urged the court that, absent proof the stroke incapacitated the driver, summary judgment for the defense was improper.

Justices and counsel also disagreed about standards at different procedural stages. Albrecht and several justices said a defendant seeking a jury instruction on the defense must produce "substantial evidence" (a lower standard than preponderance but more than speculation) to permit the instruction; others focused on the defendant's ultimate trial burden to prove medical incapacitation more likely than not. The panel probed whether evidence such as EMT observations that the defendant's right arm was flaccid and later neurologic diagnoses could be admissible corroboration, and whether background risk evidence (a declaration noting increased stroke risk for people with atrial fibrillation) improperly converts propensity into foreseeability.

Counsel discussed precedent. O'Bannon urged application of Sarton, which he said looks to what was known to the actor and evaluates foreseeability accordingly. Albrecht warned against a rule that would use risk-factor or propensity evidence to make medical conditions per se foreseeable, noting policy concerns about labeling broad classes of people as unfit to drive or shifting burdens onto plaintiffs.

Both sides agreed the parties shared some premises: the defense is affirmative and the defendant bears the ultimate burden at trial. The dispute centers on what evidence is required to get the defense to a jury and whether the court of appeals erred by imposing a test that, in counsel's view, departures from established Washington practice.

The case was submitted after argument; the court did not announce a decision from the bench. The justices will rule in writing.