Essential job functions are the fundamental duties of a position: the things a person holding the job absolutely must be able to do. Essential job functions are used to determine the rights of an employee with a disability under the Americans with Disabilities Act (ADA). An employee who can't perform the essential job functions, even with a reasonable accommodation, isn't considered qualified for the job and isn't protected from discrimination.
Under the ADA, employees are protected from disability discrimination in the workplace. However, employers don't have to hire an employee who can't do the job, regardless of whether or not the employee has a disability. Essential job functions are used to determine which employees are protected by the ADA and which are not.
An employee who is otherwise qualified (for example, because the employee has the degrees, license, and experience required for the position) is protected from disability discrimination if he or she can perform the essential job functions. It doesn't matter if the employee requires an accommodation from the employer to do so: As long as the employee can perform the essential functions of the job, with or without a reasonable accommodation, the employee is protected from discrimination by the ADA.
This is why the labeling of job functions as "essential" or "nonessential" is so important. If a function is truly essential, and an applicant or employee cannot perform it even with a reasonable accommodation, then that person is not qualified for the job as a legal matter. The person cannot bring a disability discrimination lawsuit against the employer, even if the person couldn't perform the essential job functions because of a disability. On the other hand, if a function is not truly essential, the employer cannot exclude a person with a disability from consideration for the position just because that person can't perform the function. Legally, it may not play a role in the employer's decision-making process.
As the name suggests, essential job functions are the fundamental, not marginal, duties of a job. A job duty is an essential function if any of the following is true:
In determining whether a job function is essential, the Equal Employment Opportunity Commission (the federal agency that enforces the ADA and other discrimination laws) looks at these factors:
The weight each factor receives will depend on the facts. For example, a security guard may rarely (if ever) have to use a weapon. However, the position exists to guard valuables, and a security guard who was unable to use a weapon when one was required would be at great risk (not to mention ineffective at the job).