Yes, but there are no guarantees, even with an attorney handling the Social Security disability case. A November 2003 GAO report includes the following information:
According to the General Accounting Office, of the people sampled, those without an attorney to handle their Social Security disability case are more likely to lose than win. Interesting stuff.
The entire report can be read here: http://www.gao.gov/new.items/d0414.pdf.