In the US, we have the Americans with Disabilities Act, or the ADA. This is a civil law that mandates the inclusion of all people, especially people with disabilities, in all public areas of life. This includes all electronic information and technology. Which means that, just like hotels must have ramps, you're website must be accessible to those who are deaf, blind, or unable to use a mouse.
Federal agencies also have Section 508 standards to meet.
If you need legal advice, consult with a lawyer specializing in digital accessibility law.