Many of the success criteria in the Web Content Accessibility Guidelines (WCAG) contain exceptions: situations in which meeting the requirement is impractical or impossible.
Why are exceptions necessary? For starters, WCAG is intended to be future-proof, objective, and broad. The document must be able to apply to different types of digital content. If the success criteria were too strict, they wouldn’t be effective as technical standards.
But in some cases, WCAG exceptions can lead to confusion (or, if you’re especially unlucky, debate). In this article, we’ll explain how exceptions for “essential functionality" are intended to work — and why developers should think carefully before deciding whether a certain feature qualifies as “essential.”
How WCAG Defines Essential Functionality
WCAG is published and maintained by the World Wide Web Consortium’s Web Accessibility Initiative (W3C-WAI). That group also publishes the WCAG Understanding Docs, which include definitions for key terms.
According to those documents, a function is essential if removing it:
"[...] would fundamentally change the information or functionality of the content, and information and functionality cannot be achieved in another way that would conform.”
On paper, that’s straightforward, but when you’re working on a website or mobile app, it might leave some room for interpretation.
That’s by design. Before we discuss the complexities, let’s look at a simple example.
A Basic Example of a WCAG “Essential" Exception
WCAG Success Criterion (SC) 2.5.1, “Pointer Gestures,” requires that if a function uses multipoint or path-based gestures for operation, it can also be operated with a single pointer.
But in some cases, a multipoint or path-based gesture might be essential. If you’re asking mobile users to provide a signature via their touchscreens, the multipoint gesture is essential — you couldn’t offer an alternative without losing the feature.
Depending on the implementation, you may be able to find alternatives. For example, if you’re using a signature to verify the user’s identity, you could provide another verification process (such as two-factor authentication). However, if the signature is absolutely necessary, the signature field qualifies as an exception.
When “Essential" WCAG Exceptions Get Complicated
Confusion usually occurs when a developer decides that a feature is “essential" because they don’t want to find an alternative.
Let’s say that you’ve built an animation that plays at the top of the page while the user reads content. The animation creates a sense of motion and loops indefinitely.
WCAG 2.1 SC 2.2.2, “Pause, Stop, Hide,” requires that users have a mechanism to pause autoplay content that moves, scrolls, or blinks and lasts for more than five seconds, except if the movement is part of an activity where it is essential.
A designer might argue that the animation improves the aesthetics of the page — it’s a key part of the user experience. That may be true for many people, but it’s not strictly essential, since the animation doesn’t impact the information or functionality of the page.
Aesthetics are certainly an important part of the internet. However, you can find reasonable ways to incorporate animations without creating barriers for your users.
You might allow users to disable the animations with a key press, or you could stop the animation from repeating after a few seconds. Because you’ve got options, the animation doesn’t qualify as essential.
“Technical" WCAG conformance doesn’t improve the user experience
It’s important to remember why WCAG conformance matters. The goal of the guidelines is to improve experiences for as many users as possible; arguing about technical exceptions won’t help you achieve that goal.
And while WCAG conformance aids in compliance with the Americans with Disabilities Act (ADA) and other non-discrimination laws, WCAG is a voluntary standard. It relies on self-enforcement.
As an accessibility advocate, you have a responsibility to think about the purpose of each guideline. If you decide that your content qualifies as an exception, how will that affect real users? Could you take simple steps to provide a more equitable experience?
In most cases, the answer is “yes.” By working with a qualified accessibility partner, you can remove barriers without sacrificing aesthetics or functionality. While finding the best solution for each issue may require some work, it’s well worth the effort.
Over 1 billion people worldwide live with disabilities. When you commit to the principles of WCAG, you show those users that you respect their time — and ultimately, every user benefits.