49 CFR 209.611: Informal response and assessment.

(a) If a respondent elects to make an informal written response to a demand letter, respondent must submit to the Office of the Chief Counsel such written explanations, information, or other materials as respondent may desire in answer to the charges or in mitigation of the proposed penalty.

(b) Instead of or in addition to an informal written response as described in paragraph (a), an informal response may consist of a request for a conference.

(c) Written explanations, information, or materials submitted by the respondent, and relevant information presented during any conference held under this section, are considered by the Office of the Chief Counsel in reviewing the demand letter and determining the fact of violation and the amount of any penalty to be assessed.

(d) After consideration of an informal response, including any relevant information presented at a conference, the Office of the Chief Counsel may dismiss the demand letter in whole or in part. If the Office of the Chief Counsel does not dismiss it in whole, the Office of the Chief Counsel may enter into a settlement agreement or enter an order assessing a civil penalty.