21 CFR 20.62: Inter- or intra-agency memoranda or letters.

Interagency or intra-agency memoranda or letters that would not be available by law to a party other than an agency in litigation with the Food and Drug Administration may be withheld from public disclosure except that factual information that is reasonably segregable in accordance with the rule established in § 20.22 is available for public disclosure. The deliberative process privilege shall not apply to records created 25 years or more before the date on which the records were requested.