“Nothing about us without us” is the global slogan for the disability rights movement. It means that nothing should be decided about people with disabilities without their presence, their participation, and their inclusion.
The disability rights movement has been evolving for a long time, but in the US, it really gained momentum from the civil rights movement. There were people with disabilities who used the tactics of the civil rights movement: sit-ins, protests, and marches to bring disability rights to everyone’s attention. Eventually, that led to the Americans with Disabilities Act [passed in 1990].