Legal precedent is changing, and ADA compliance related lawsuits are becoming more successful, and the courts are seeing more of them as a result. Title III of the Americans with Disabilities Act pertains to private sector businesses. Lately, those protections are more frequently expanding into digital territory as web and mobile applications become more necessary in our day-to-day lives.
Hey Casey, this is one of the areas where things get a little weird because the W3 doesn’t actually have any say over the ADA guidelines, it is more than the ADA guidelines adopted the WCAG 2.0 guidelines as just that, a guideline to help. As far as I know, the tool you’ve linked to hasn’t been used in any judgements I’m aware of. Usually when it comes down to making a decision on if something is/isn’t compliant they have people use the actual PAWS tools and show what elements do/don’t work as intended or are otherwise inaccessible. Hope this helps!
The Department of Justice’s revised regulations for Titles II and III of the Americans with Disabilities Act of 1990 (ADA) were published in the Federal Register on September 15, 2010. These regulations adopted revised, enforceable accessibility standards called the 2010 ADA Standards for Accessible Design, "2010 Standards." On March 15, 2012, compliance with the 2010 Standards was required for new construction and alterations under Titles II and III. March 15, 2012, is also the compliance date for using the 2010 Standards for program accessibility and barrier removal.
If you do get sued, if you immediately remediate your website, you may be able to get the lawsuit dismissed on mootness (there’s no longer anything in dispute, i.e. plaintiffs are arguing your website is inaccessible but you’ve already made it accessible). This definitely does not mean you should wait to fix your website but it does mean you may have an out.

Case law has been the most helpful in illuminating the implications of the ADA for websites.There have been lawsuits involving companies like Expedia,, Southwest Airlines, and Target as defendants and primarily featuring accessibility organizations as plaintiffs. These cases had mixed results, but each helped clarify the ADA's jurisdiction on the web. 
The ADA requires that title II entities (State and local governments) and title III entities (businesses and nonprofit organizations that serve the public) communicate effectively with people who have communication disabilities. The goal is to ensure that communication with people with these disabilities is equally effective as communication with people without disabilities.