WCAG 2.0 / 2.1 are stable, referenceable, technical AND international system of coding standards. It has 12-13 guidelines that are organized under four principles: perceivable, operable, understandable, and robust. For each guideline, there are testable success criteria, which are attainable in three levels: A, AA, and AAA.
The World Wide Web Consortium (W3C) sets the main international standards for the World Wide Web and its accessibility. W3C created the Web Content Accessibility Guidelines (WCAG 2.0) which are similar to Section 508, but on an international level. Section 508 Amendment to the Rehabilitation Act of 1973 require Federal agencies to make their electronic and information technology accessible to people with disabilities.
At the time of this writing, there is no law (in the USA) that requires the general public to be in compliance with WCAG 2.0 standards. However, websites related to federal government agencies, with some exceptions, require that their websites must be fully accessible and in compliance with WCAG 2.0 Level AA.
The AODA was enacted in June 2005, with five sections that have various compliance dates beginning in 2010. New public websites, significantly refreshed websites, and any web content posted after January 1, 2014, must meet WCAG 2.0 Level A Guidelines.
EU Directive 2016/2102/EU published on December 2, 2016, is an EU legal act to make public sector websites and mobile applications accessible across the EU. EU countries must adopt measures to incorporate the directive into national law before September 23, 2018, in order to achieve the objectives set by the directive.
Access to information and communication technology (ICT) is addressed by the standards and guidelines issued under Section 508 of the Rehabilitation Act and Section 255 of the Communications Act. In January 2017, this regulation was revised to include WCAG 2.0 standards with compliance expected beginning January 2018.
The Revised 508 Standards include a "safe harbor" provision for existing ICT. Under this safe harbor, unaltered existing ICT (including content) that complies with previous 508 Standards does not need to be modified or upgraded to conform to the Revised 508 Standards.
This safe harbor applies on an element-by-element basis, so each component or portion of existing ICT is assessed separately.