28 CFR §2.74

1. (a)Following each initial or subsequent hearing, the Commission shall render a decision granting or denying parole, and shall provide the prisoner with a notice of action that includes an explanation of the reasons for the decision. The decision shall ordinarily be issued within 21 days of the hearing, excluding weekends and holidays.
2. (b)Whenever a decision is rendered within the applicable guideline established in this subpart, it will be deemed a sufficient explanation of the Commission's decision for the notice of action to set forth how the guideline was calculated. If the decision is a departure from the guidelines, the notice of action shall include the reasons for such departure.
3. (c)All decisions may be made by one Commissioner, except that if the Commissioner does not concur with a panel recommendation, the case shall be referred to another Commissioner for a vote and the decision shall be based on the concurring votes of two Commissioners.