Understanding Essential Functions of the Job under the ADA

When it comes to workplace accommodations, one of the most important, and often misunderstood, concepts under the Americans with Disabilities Act (ADA) is “essential job functions.” Essential functions are the crucial job duties performed by an employee, with or without reasonable accommodation process. The distinction between what’s “essential” and what’s “marginal” can determine whether an individual is considered qualified for a position, and whether an employer must modify a role to provide a fair opportunity.

Both federal law and state laws in California, New York, and Washington add extra layers of protection, often holding employers to higher standards of fairness and documentation.

Defining Essential Job Functions

Core Duties vs. Marginal or Secondary Tasks

Under the ADA, an “essential function” refers to a fundamental duty that is intrinsic to the position — not peripheral or marginal functions. Does a function require specialized expertise? For instance, operating heavy machinery is an essential function for a forklift operator, but attending optional company social events is not.

Courts and state agencies (like California’s Civil Rights Department or New York’s Division of Human Rights) look at several factors to determine whether a duty is essential:

• Why the position exists. If a job exists primarily to perform a specific task, that task is almost certainly essential.
• Number of employees available to perform it. If only one person can do it, it’s more likely essential.
• Impact if the function isn’t performed. If leaving out a task fundamentally changes the job, it’s essential.

Tasks that are marginal or secondary, like light administrative work, maybe a customer service position, occasional lifting, or optional travel, typically don’t define whether someone is “qualified” under the ADA. Employers cannot deny accommodations or terminate someone based on their inability to perform nonessential duties.

How Job Descriptions and Actual Practice Are Weighed

While written job descriptions are key, they aren’t the final word. The ADA requires an analysis of what employees actually do day-to-day. For example, if a job description lists the position’s essential functions include “standing for eight hours” as essential, but in reality employees sit for most of the day, that requirement may not hold up legally.

California and Washington courts, in particular, have emphasized that real-world evidence outweighs formal paperwork. In Hernandez v. Rancho Santiago Cmty. Coll. Dist. (Cal. Ct. App. 2018), the court found that a teacher’s essential duties had to be evaluated based on actual practice, not outdated job descriptions. Similarly, New York’s Human Rights Law (NY Exec. Law §296) allows employees to challenge essential function definitions that don’t reflect reality.

Why Essential Functions Matter

Determining Whether an Employee Is “Qualified”

The ADA (and parallel state laws like California’s Fair Employment and Housing Act and Washington’s Law Against Discrimination) defines a qualified individual as someone who can perform the essential functions of the job, with or without reasonable accommodation.

This means an employee doesn’t have to perform every single task — only the essential ones.

How Essential Duties Affect Reasonable Accommodation Requests

When an employee requests a reasonable accommodation — such as modified hours, assistive technology, or task reassignment — the employer must determine whether that accommodation allows the person to perform the essential functions.

However, the law doesn’t require employers to remove or fundamentally alter an essential function. For example, a delivery driver must still be able to drive; an accommodation that removes that duty entirely would be unreasonable.

Employer vs. Employee Perspectives

Employer Discretion in Defining Roles

Employers have discretion to define job roles – with limits. The ADA allows employers to identify essential functions related in job postings, descriptions, and policy documents. Still, courts will closely examine whether those definitions reflect business necessity and actual practice.

In California, for example, employers must ensure job descriptions are up-to-date, specific, and directly tied to legitimate business needs. Listing too many “essential” duties — especially minor or rarely performed ones — can backfire in a legal dispute.

Employee Rights to Challenge Unfair Classifications

Employees aren’t powerless when employers misuse the term “essential” to justify discrimination or denial of accommodations. Under both the ADA and state laws, employees can present evidence — such as witness statements, schedules, or performance reviews — to show that certain duties are not truly essential.

How Courts and the EEOC Determine Essential Functions

When a disability or medical limitation affects someone’s ability to perform their job, one question becomes the legal pivot point: What are the “essential functions” of that position? Both the Equal Employment Opportunity Commission (EEOC) and federal and state courts spend time defining, testing, and interpreting this concept. The ADA decides whether an employee is qualified and what accommodations an employer must provide.

Legal Standards and Guidelines

ADA Requirements on Essential Functions

A person qualifies for a job if they can perform core duties with or without a reasonable accommodation. The distinction is critical: an employer cannot deny someone a job — or fire them — because they cannot perform nonessential tasks.

EEOC Factors: Time Spent, Consequences, and Business Necessity

The EEOC outlines several key factors that determine whether a function is essential:

1. The amount of time spent performing the function.
2. The consequences of not performing the function.
3. The employer’s written job description, especially if prepared before hiring.
4. The work experience of current or past employees in the position.
5. The employer’s judgment as to which duties are essential.
6. The terms of a collective bargaining agreement, if one applies.

The EEOC’s approach blends structure and flexibility. A function can be essential even if rarely performed, if failing to perform it would cause significant harm to the business or safety.

Evidence Courts Consider

Written Job Descriptions

Courts give weight to written job descriptions, especially if they were created before a dispute arises. However, they are not conclusive. In California and Washington, judges often look beyond formal descriptions to ensure employers aren’t using outdated or inflated lists to justify excluding workers with disabilities.

For example, if a particular job posting says a receptionist “must lift 25 pounds,” but no one in that role ever lifts anything heavier than a file folder, that “requirement” won’t likely be treated as essential. The ADA and corresponding state laws emphasize function over form — what the employee actually does matters more than what’s on paper.

Supervisor Testimony and Work Experience

Courts and the EEOC also weigh testimony from supervisors and coworkers who can describe what tasks are truly critical.

In Washington, for instance, state agencies often consider whether removing or reassigning a duty would impose an “undue hardship” on the employer. That connects directly to whether a function is essential. If removing it would make the job unworkable, it’s probably essential.

Comparison With Others in the Role

Perhaps the most practical factor courts look at is how other employees in similar roles perform the job. If other workers with similar titles or duties don’t perform a certain task, or perform it only occasionally, it’s difficult for an employer to claim that task is essential.

Work-Specific Examples

Does a Function Determine Disputes?

Disputes often arise when employers overstate job demands or fail to update job descriptions. In Hernandez v. Rancho Santiago Cmty. Coll. Dist. (Cal. 2018), the court ruled that standing for long periods wasn’t essential for a teaching role because most instruction occurred while seated. Similarly, New York courts have found that certain physical requirements, like heavy lifting or extensive travel, were not essential when they weren’t regularly required in practice.

Lessons for Employers and Employees

Employers, and even those in a floating supervisor job, should document job functions carefully, review them regularly, and ensure they reflect real-world duties. Inflated or outdated job descriptions can expose employers to liability.

Employees should know that understanding what’s truly essential can protect their rights. If an employee faced a denial of accommodation or termination, they should gather evidence: job postings, coworker statements, and performance records that show what’s actually required.

Questions about essential functions of a job? Call Lawyers for Justice, P.C. for a free consultation.