What are the implications of ADA for web mapping, particularly for those who are color blind?

The Americans with Disabilities Act of 1990 (ADA) prohibits discrimination and ensures equal opportunity for persons with disabilities in employment, State and local government services, public accommodations, commercial facilities, and transportation. It also mandates the establishment of TDD/telephone relay services. The ADA was revised by the ADA Amendments Act of 2008 (P.L. 110-325), which became effective on January 1, 2009. The ADA is codified at 42 U.S.C. 12101 et seq. What are the implications of ADA for web mapping, particularly for those who are color blind? – support what you write with an example and citation/evidence.