Kansas Supreme Court Reiterates: “Idiopathic” and “Unknown” Are Not Synonyms

Case Sent Back to Board for Determination Consistent With its Holding

In a case of first impression, the Supreme Court of Kansas, affirming a decision of the state’s Court of Appeals, held that “idiopathic” is not a synonym for “unknown” [Estate of Graber v. Dillon Cos., 2019 Kan. LEXIS 67 (Apr. 12, 2019)]. Quoting Larson’s Workers’ Compensation Law extensively, the high court defined “idiopathic causes,” which may not be used to establish a workers’ compensation claim [see Kan. Stat. Ann. § 44-508(f)(3)(A)(iv)(2018)], as medical conditions or medical events of unknown origin that are peculiar to the injured individual [emphasis added]. The Court stressed that the plain language of the statute rendered an injury non-compensable only upon proof the injury or accident arose directly or indirectly from a medical condition or medical event of unknown origin peculiar to the claimant. Accordingly, the Court remanded the case back to the state’s Workers’ Compensation Appeals Board (“Board”) for additional consideration.


Graber was injured when he fell down a workplace stairway. The accident’s cause remains a mystery. Graber had no direct recollection of falling and there were no witnesses. The Board denied Graber’s claim. It construed the statutory “idiopathic causes” exclusion broadly to cover all unknown causes. A Court of Appeals panel reversed, defining the term more narrowly [Graber v. Dillon Companies, 52 Kan. App. 2d 786, 377 P.3d 1183 (2016)]. Graber’s employer petitioned the Kansas Supreme Court for review.

2011 Amendment

At the core of the dispute was a 2011 amendment to the Kansas Workers’ Compensation Act, which provides, in relevant part, that benefits may not be awarded if the accident or injury “arose either directly or indirectly from idiopathic causes” [Emphasis added; Kan. Stat. Ann. § 44-508(f)(3)(A)(iv)(2018)].

Arising Out of and in the Course of Employment

Initially, the Supreme Court repeated the usual compensation formula, that benefits are to be paid for repetitive trauma or occupational disease arising out of and in the course of employment …” [Kan. Stat. Ann. § 44-501b(b)(2018)]. The Court added that the two phrases have separate and distinct meanings; they are conjunctive, and each condition must exist before compensation is allowable.

The employer argued that Graber’s accident arose directly from an idiopathic cause and as such, the accident did not arise out of his employment. The Court said, however, that closer analysis rebutted the employer’s claim that “idiopathic” means merely “spontaneous” and “unknown.”

Types of Risk

According to the Court, the employer had suggested this progression of thought: (1) the “neutral risk” exclusion pertained only to accidents or injuries with known causes [here the employer cited Hensley v. Glass, 226 Kan. 256, 597 P.2d 641 (1979)(“Hensley”)]; and a (2) claimant’s medical condition or other weakness was a personal risk; therefore (3) the only way to give effect to the term “idiopathic” was to define it as “unknown.”

The Court said the employer’s point was flawed. Even if there was some redundancy with either the personal risk or neutral risk exclusions, that redundancy did not require a different definition of “idiopathic.”

Employer’s Argument Ignored Full Reading of The Argument’s Source: Larson

The Court continued that the distinction the employer advocated based on its facts “ignored the source of Hensley‘s ‘neutral’ characterization—Larson’s treatise” [opinion, p. 24]. According to the Court, Professor Larson conceptualized various risk categories as encompassing all possible risks that could result in a workplace injury. The Court continued that Larson defined risks distinctly associated with employment and personal risks as the two ends of the risk continuum. The former “comprises all the obvious kinds of injury that one thinks of at once as industrial injury … machinery breaking, objects falling, explosives exploding, tractors tipping, fingers getting caught in gears, excavations caving in, and so on …” [quoting Larson, § 4.01]. The latter includes “origins of harm so clearly personal that, even if they take effect while the employee is on the job, they could not possibly be attributed to the employment” [quoting Larson, § 4.02].

The Court observed that Larson defined the third category, neutral risks, expansively to mean any risks that have no particular employment or personal character [Larson, § 4.02]. Again quoting Larson, the Court said,

Another kind of neutral-risk case is that in which the cause itself, or the character of the cause, is simply unknown. An employee may be found to have died on the job from unexplained causes, or he or she may suffer a slip or fall for no reason that anyone, including the employee, can explain. An employee may be attacked by unknown persons, whose motives may have been personal or related to the employment.” (Emphases added by Court) [Larson’s, § 4.03].

Court’s Conclusion

The Court concluded that the plain language of K.S.A. 2018 Supp. 44-508(f)(3)(A)(iv) rendered an injury non-compensable only upon proof the injury or accident arose directly or indirectly from a medical condition or medical event of unknown origin peculiar to the claimant. The Court added, “The term ‘idiopathic’ as used in the caselaw and its definition in workers compensation treatises add persuasive heft to this conclusion” [opinion pp. 28-29].

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