I interpreted the question differently -- in that rights seeking groups operate within liberal democracies.
Neither select unions nor the disability movement (DRM) has dealt with macroeconomic issues under capitalism such as the reserve army of labor. To me they both have narrow vision reliant upon capitalist power relations. The select unions are usually most interested in their wealth maximization -- via higher wages, better health care, etc. which can be interpreted as partial social justice, not total, and the DRM is interested in getting some disabled persons employment under the existant system but cannot (with a civil rights approach) make this possible for all of the unemployed disabled who would like a job,which, again, is partial social justice.
Each are more interested in their slice of pie than changing the pie itself. marta --