No, you do not need a doctor’s opinion.  However,  your treating doctor’s opinion about your physical and/or mental limitations can be very effective in winning Social Security Disability Benefits if it is supported by objective evidence.  This is one area where being represented by an attorney can be very beneficial.  A Social Security Disability attorney knows the guidelines for determining if a claimant would be found disabled.  Therefore, the attorney knows the questions to ask the doctor which would be most helpful to the judge.  It is not sufficient for the doctor to write a blanket statement that says “My patient is disabled and cannot work.”  The judge will tell you that this is a matter for him to decide.  While such a statement by a doctor would be evidence, it is not very persuasive.  It is much better to have the doctor write a letter or answer questions about your ability to lift, sit, stand, walk, etc. if placed in a competitive work environment.  Further, if the opinion is coming from your treating doctor, then the judge must give the doctor’s opinion greater weight and credibility than an opinion by a non-treating doctor as long as the opinion is supported by objective medical evidence.