When standards are adopted by a governing body they become part of the regulatory code of that body. These standards (or regulations or codes) are no longer voluntary and must be adhered to by the affected parties.
"The U.S. Access Board is a federal agency that promotes equality for people with disabilities through leadership in accessible design and the development of accessibility guidelines and standards for the built environment, transportation, communication, medical diagnostic equipment, and information technology."
The Iowa State Building Code Bureau is within the State Fire Marshal Division of the Iowa Department of Public Safety. The mission of this bureau is to ensure the construction of safe and accessible buildings.