Actually disability laws apply to ost western countries. The USA has its own version of the law but I am not exactly sure of the penalties.
When talking about accessibility most people are referring to disabled users but many forget to talk about bots, spiders and browsers. All these applications will also be affected by the accessibility of your site.
Coding Standards are the main thing. But there are also some special design procedures you should undertake. I have written an article about it which you can find on my website
Idevs or it is around on this forum somewhere if I can find it.
Jamie