Essential job functions refer to the fundamental job duties of an individual position. They are the primary job duties that are fundamental to the position.
Essential job functions will be provided in the employer’s judgment of the essential job functions, a written job description prepared before advertising or interviewing employees or applicants for the individual position.
The following is an example of a case law on essential job functions:
An employee's ability to perform all essential job functions without accommodation is a factor weighing against the reasonableness of an accommodation, not necessarily a complete bar to any claim by an employee needing to take insulin shots to prevent diabetic reactions. [Nawrot v. CPC Int'l, 259 F. Supp. 2d 716 (D. Ill. 2003)].