California Code, Education Code - EDC § 22126

“Disability” or “disabled” means any medically determinable physical or mental impairment that is permanent or that can be expected to last continuously for at least 12 months, measured from the onset of the disability, but no earlier than the day following the last day of actual performance of service that prevents a member from performing the member's usual duties for the member's employer, the member's usual duties for the member's employer with reasonable modifications, or the duties of a comparable level position for which the member is qualified or can become qualified within a reasonable period of time by education, training, or experience. Any impairment from a willful self-inflicted injury shall not constitute a disability.