49 C.F.R. § 511.12 – Answer.

(a) Time for filing. A respondent shall have twenty (20) days after service of a complaint within which to file an answer.
(b) Content of answer. An answer shall conform to the following:
1. (1) Request for hearing. Respondent shall state whether it requests a full, adjudicatory hearing or whether it desires to proceed on the basis of written submissions. If a hearing is requested, respondent shall specify those issues on which a hearing is desired.
2. (2) Contested allegations. An answer in which the allegations of a complaint are contested shall contain:
  1. (i) Specific admission or denial of each allegation in the complaint. If the respondent is without knowledge or information sufficient to form a belief as to the truth of an allegation, respondent shall so state. Such a statement shall have the effect of a denial. Denials shall fairly meet the substance of the allegations denied. Allegations not thus answered shall be deemed to have been admitted.
  2. (ii) A concise statement of the factual and/or legal defenses to each allegation of the complaint.
3. (3) Admitted allegations. If the respondent admits or fails to deny any factual allegation, he or she shall be deemed to have waived a hearing as to such allegation.
(c) Default. Failure of the respondent to file an answer within the time provided (or within an extended time, if provided), shall be deemed to constitute a waiver of the right to appear and contest the allegations set forth in the complaint and to authorize the Presiding Officer to make such findings of fact as are reasonable under the circumstances.