We are amending our rules to clarify that we apply the preponderance of the evidence standard when we make determinations and decisions at all levels of our administrative review process. These rules do not change our policy that the Appeals Council applies the substantial evidence standard when it reviews a decision by an administrative law judge (ALJ) to determine whether to grant a request for review. We are also adding definitions of the terms "substantial evidence" and "preponderance of the evidence" for use in applying these rules.