This Act is Federal Civil Rights Legislation, and is one of the areas of regulation that every architect must insure that he or she is addressing in all building designs. No drawings are required to be submitted to enforce the ADA, but the act is enforceable on a Federal Level.
Some localities (Santa Clarita not excluded) have had lawyers in wheelchairs come through buildings and, having found at times areas that are not up to the federal code, will file lawsuits against the owner of the building in order to insure that the building will meet ADA. The owner is responsible to insure that the building meets all codes on federal, state and local levels.
Part of the benefit of hiring an architect is that the architect is familiar with the legislation and can incorporate into his drawings the ADA requirements necessary.