Basically, there are standards which apply to US federal agencies, and State or Local Government websites (not business/personal websites). While some disability discrimination laws do mention websites, they don’t specify the technical standards required to comply with the law. Regardless of ADA’s lack of stating websites must be fully accessible, the Department of Justice seems to rule on the side of “they should be”.
On the legal side, ambiguity in the law and the speed at which technology and dependence on the Internet has developed created an opportunity for litigation all over our nation. As these cases have moved through our system, the courts have been nearly split -- with the 1st, 3rd and 7th Circuits ruling that the ADA does apply to websites, while the 6th, 9th and 11th Circuits have ruled that it does not. These latter rulings have all been based on the interpretation that the ADA is focused on physical location and requires a nexus test. Other circuit courts in the United States have yet to rule on the topic.