20 C.F.R. § 220.58
A claimant or his or her representative may object to his or her being examined by a designated physician or psychologist. If there is a good reason for the objection, the Board will schedule the examination with another physician or psychologist. A good reason may be where the consultative examination physician or psychologist had previously represented an interest adverse to the claimant. For example, the physician or psychologist may have represented the claimant's employer in a worker's compensation case or may have been involved in an insurance claim or legal action adverse to the claimant. Other things the Board will consider are: language barrier, office location of consultative examination physician or psychologist (2nd floor, no elevator, etc.), travel restrictions, and examination by the physician or psychologist in connection with a previous unfavorable determination. If the objection is because a physician or psychologist allegedly "lacks objectivity" (in general, but not in relation to the claimant personally) the Board will review the allegations. To avoid a delay in processing the claimant's claim, the consultative examination in such a case will be changed to another physician or psychologist while a review is being conducted. Any objection to use of the substitute physician or psychologist will be handled in the same manner. However, if the Board or the Social Security Administration had previously conducted such a review and found that the reports of the consultative physician or psychologist in question conform to the Board's guidelines, then the Board will not change the claimant's examination.
20 C.F.R. § 220.58