Montana Title 39. Labor § 39-71-119. Injury and accident defined

(a) internal or external physical harm to the body that is established by objective medical findings;

(b) damage to prosthetic devices;

(c) damage to appliances, except for damage to eyeglasses, contact lenses, dentures, or hearing aids; or

(d) death.

(a) an unexpected traumatic incident or unusual strain;

(b) identifiable by time and place of occurrence;

(c) identifiable by member or part of the body affected; and

(d) caused by a specific event on a single day or during a single work shift.

(a) emotional or mental stress; or

(b) a nonphysical stimulus or activity.

(5)(a) A cardiovascular, pulmonary, respiratory, or other disease, cerebrovascular accident, or myocardial infarction suffered by a worker is an injury only if the accident is the primary cause of the physical condition in relation to other factors contributing to the physical condition.

(b) “Primary cause”, as used in subsection (5)(a), means a cause that, with a reasonable degree of medical certainty, is responsible for more than 50% of the physical condition.