19 C.F.R. § 165.42
Any party to the investigation, regardless of whether it submitted a request for administrative review, may submit a written response to the filed request(s) for review. A party who submitted a request for administrative review may not respond to its own submission. Each written response may not exceed 30 pages in total (including exhibits but not table of contents or table of authorities) and must follow the requirements in § 165.41(f) . The written responses to the request(s) for review must be limited to the issues raised in the request(s) for review and must be based solely on the facts already on the administrative record in that proceeding. The responses must be filed in a manner prescribed by CBP no later than 10 business days from the commencement of the administrative review. All responses must be accompanied by the certifications provided for in § 165.5 . Each party seeking business confidential treatment must comply with the requirements in § 165.4 . The public version of the response(s) to the request(s) for review must be provided to the other parties to the investigation via an email message or through any other method approved or designated by CBP.
19 C.F.R. §165.42