There are many ways to discriminate against people based on disabilities, including psychological ones. Anyone known to have a history of mental disorders can be considered disabled. Employers with more than 15 employees must take care to treat all employees fairly and with any accommodations needed. Even when an employee is doing a job exceptionally well, she or he is not necessarily no longer disabled; employers must continue to follow all policies for the disabled.
I should mention one caveat to all of this. Businesses that are required to comply but don't have the ability to bring their websites into compliance can provide an accessible alternative to provide the same information, goods, and services that they provide online, like a staffed phone line. The trick, however, is that this option has to provide at least equal access, including in terms of hours of operation. And, as we know, the internet is around 24/7, so good luck with that.
The Department has assembled an official online version of the 2010 Standards to bring together the information in one easy-to-access location. It provides the scoping and technical requirements for new construction and alterations resulting from the adoption of revised 2010 Standards in the final rules for Title II (28 CFR part 35) and Title III (28 CFR part 36).