ADA, Section 508, and WCAG are three different things that people often confuse. The ADA is a civil-rights law. Section 508 is a federal procurement rule. WCAG is the technical standard both rely on to define “accessible.” Put simply: the law says you must comply, and WCAG says how.
The one-sentence version
- The ADA (Americans with Disabilities Act) is the law that says businesses and services open to the public can’t discriminate against people with disabilities — including online.
- Section 508 is a section of the Rehabilitation Act that says federal agencies and the vendors who sell to them must make their technology accessible.
- WCAG (Web Content Accessibility Guidelines) is the published technical standard — written by the W3C’s Web Accessibility Initiative — that spells out, in testable detail, what “accessible” means.
Two of these are laws. One is a standard. The laws point to the standard. That single relationship clears up most of the confusion.
Comparison table: ADA vs Section 508 vs WCAG
| ADA | Section 508 | WCAG | |
|---|---|---|---|
| What it is | Civil-rights law | Federal procurement rule | Technical standard |
| Who wrote it | U.S. Congress | U.S. Congress (Rehabilitation Act) | W3C / WAI |
| Who it covers | Most businesses open to the public; state & local government | Federal agencies and their tech vendors | Anyone — it’s a standard, not a law |
| Enforced by | DOJ, private lawsuits | Federal agencies, civil rights complaints | Not enforced — referenced by laws |
| Names WCAG? | Not in statute (but courts/DOJ use it) | Yes — formally incorporates WCAG | It is WCAG |
| Practical target | WCAG 2.1 AA | WCAG 2.0 AA (per the rule) | 2.1 / 2.2 AA |
| Typical trigger | Demand letter or lawsuit | Procurement / VPAT request | Audit benchmark |
The key takeaway: the columns aren’t competitors. WCAG is the ruler; the ADA and Section 508 are two different laws that pick up that ruler.
ADA: the law most businesses live under
The Americans with Disabilities Act became law in 1990, before the modern web. Title III covers “places of public accommodation” — retailers, restaurants, law firms, healthcare providers, hotels, and the like. Courts have widely read Title III to cover business websites, which is why thousands of ADA web-accessibility lawsuits are filed each year and many more demand letters go out quietly.
The ADA’s text doesn’t list HTML success criteria. So how do you comply? In practice, the DOJ, courts, and settlement agreements treat WCAG 2.1 AA as the benchmark. Meeting WCAG is how a business demonstrates its site is accessible. (For the legal mechanics, see ADA Title III & websites. This is general information, not legal advice — talk to an attorney about your specific exposure.)
If you’ve already received a notice, our got an ADA demand letter guide walks through what to do first.
Section 508: the federal procurement rule
Section 508 of the Rehabilitation Act is narrower than people assume. It applies to federal agencies and the companies that sell information technology to them. If you run a private bakery, coffee shop, or local services site, Section 508 almost certainly doesn’t apply to you directly.
What makes Section 508 important to know is that, in its 2017 “refresh,” it formally incorporated WCAG 2.0 Level AA by reference. That was a turning point: it made WCAG the official federal technical baseline. When a federal or enterprise buyer asks for a VPAT (Voluntary Product Accessibility Template), they’re asking you to document your product against Section 508 and WCAG. We produce those as a VPAT / accessibility conformance report.
So Section 508 and the ADA are different laws with different audiences — but they converge on the same standard.
WCAG: the standard both laws lean on
WCAG is where “accessible” stops being abstract. It’s organized around four principles, known by the acronym POUR — content must be Perceivable, Operable, Understandable, and Robust. Within those principles are testable success criteria, each assigned a conformance level:
- Level A — the most basic, must-have requirements.
- Level AA — the practical compliance target for almost everyone; this is what the ADA settlements and Section 508 reference.
- Level AAA — the strictest, rarely required across an entire site.
WCAG covers the things real users depend on: meaningful alt text for images, sufficient color contrast, full keyboard navigation, and correct use of ARIA so assistive technology — screen readers like NVDA, JAWS, and VoiceOver — can announce the page accurately. For a business-friendly walkthrough, start with WCAG explained for business owners and the specifics in WCAG 2.1 AA explained.
The reason WCAG 2.1 AA is the de facto answer to “which standard?” is that it’s the version most courts, the DOJ, and Section 508-adjacent guidance converge on. WebAIM’s research on real-world failures — see WebAIM — consistently finds the same handful of issues (missing alt text, low contrast, empty links, missing form labels) on the vast majority of homepages. Those are exactly the criteria an audit measures and a remediation fixes.
How they fit together in one picture
Think of it as a stack:
- A law applies to you. For most private businesses, that’s the ADA (Title III). For federal agencies and their vendors, it’s also Section 508.
- The law points to a standard. Section 508 names WCAG explicitly; the ADA does so through DOJ guidance, court decisions, and settlements.
- The standard is WCAG. Target 2.1 Level AA.
- You prove it with testing. A real audit — combining automated scans with manual testing — checks each success criterion, and remediation fixes what fails.
That’s the whole relationship. Different starting points, same destination.
Why overlays don’t satisfy any of them
A common shortcut is an accessibility overlay — a single line of JavaScript that promises instant compliance. It doesn’t deliver. Overlays can’t reliably meet WCAG success criteria, they often break keyboard navigation and screen-reader output, and they satisfy neither the ADA nor Section 508. Plaintiffs have specifically named sites that rely on them. We cover the evidence in why overlays don’t work and overlay vs manual remediation.
The only durable path is fixing the underlying code. That’s what manual remediation means: a human correcting the markup, contrast, labels, and focus order so the page works with real assistive technology — not a widget pretending it does.
What to do next
If you’re trying to figure out which obligations apply and where your site stands, start by seeing the actual issues. Curbcut’s free accessibility scan shows you where your site measures up against WCAG 2.1 AA, and our accessibility remediation team fixes the findings by hand — no overlay, no shortcuts. For the broader context, the ADA website compliance pillar ties the law, the standard, and the fix together.