The U.S. Department of Transportation enforces regulations governing transit, which includes ensuring that recipients of federal aid and state and local entities responsible for roadways and pedestrian facilities do not discriminate on the basis of disability in highway transportation programs or activities. The department also issues guidance to transit agencies on how to comply with the ADA to ensure that public transit vehicles and facilities are accessible.
Until the ADA is updated to address the special case of website accessibility, or the Department of Justice releases its website accessibility regulations, complying with WCAG 2.0 Level AA is the best way to ensure that people with disabilities have equal access to your website. The overview below is a great starting point about meeting the WCAG 2.0 Level AA recommendations.

You may have installed a ramp, increased the width of your door frames, or made other accommodations to ensure that your physical premises are accessible to all. The requirement for equal access used to only apply to physical locations and storefronts, but now the government is actively ensuring that the requirements for ADA accessibility include online properties such as websites and mobile apps.
Two agencies within the U.S. Department of Labor enforce parts of the ADA. The Office of Federal Contract Compliance Programs (OFCCP) has coordinating authority under the employment-related provisions of the ADA. The Civil Rights Center (CRC) is responsible for enforcing Title II of the ADA as it applies to the labor- and workforce-related practices of state and local governments and other public entities. Visit the Laws & Regulations subtopic for specific information on these provisions.
On September 25, 2008, President George W. Bush signed the ADA Amendments Act of 2008 (ADAAA) into law. The amendment broadened the definition of "disability", thereby extending the ADA's protections to a greater number of people.[43] The ADAAA also added to the ADA examples of "major life activities" including, but not limited to, "caring for oneself, performing manual tasks, seeing, hearing, eating, sleeping, walking, standing, lifting, bending, speaking, breathing, learning, reading, concentrating, thinking, communicating, and working" as well as the operation of several specified major bodily functions.[43] The act overturned a 1999 US Supreme Court case that held that an employee was not disabled if the impairment could be corrected by mitigating measures; it specifically provides that such impairment must be determined without considering such ameliorative measures. It also overturned the court restriction that an impairment which substantially limits one major life activity must also limit others to be considered a disability.[43] In 2008, the United States House Committee on Education and Labor stated that the amendment "makes it absolutely clear that the ADA is intended to provide broad coverage to protect anyone who faces discrimination on the basis of disability."[44] Thus the ADAAA led to broader coverage of impaired employees.
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!
Additionally, in February 2018, Congress passed the ADA Education and Reform Act, a bill designed to make it harder for disabled Americans to sue businesses for discrimination. Republican lawmakers who wrote and passed the bill argue that the law will help curb “frivolous” lawsuits, while opponents have argued that this law will gut the ADA, essentially giving businesses little reason to follow the ADA guidelines at all.
Talk to your web designer about other techniques that will make your site more user-friendly for people with disabilities. Worried that’s not in your budget? Consider the fact that DOJ fines start at $75,000. And it's still yet to be determined if a non-compliant website is liable for one fine or will be charge per page for each violation. As the recent lawsuits illustrate, though, settlements quickly add up into the millions.