14 C.F.R. § 406.103
For the purpose of this part:
Administrative law judge means an administrative law judge appointed pursuant to the provisions of 5 U.S.C. 3105 .
Attorney means a person licensed by a state, the District of Columbia, or a territory of the United States to practice law or appear before the courts of that state or territory.
Complainant in a civil penalty action means the proponent of the civil penalty in the FAA.
FAA decisionmaker means the Associate Administrator for Commercial Space Transportation, or the Administrator of the Federal Aviation Administration, acting in the capacity of the decisionmaker on appeal; or a person who has been delegated the authority to act for the FAA decisionmaker. As used in this part, the FAA decisionmaker is the official authorized to issue a final decision and order of the Secretary in an action.
Mail means U.S. first class mail, U.S. certified mail, U.S. registered mail, or an express courier service.
Party means the respondent or the complainant.
Personal delivery includes hand-delivery or use of a same-day messenger service. "Personal delivery" does not include the use of Government interoffice mail service.
Properly addressed means using an address contained in agency records; a residential, business, or other address used by a person on any document submitted under this part; or any other address determined by other reasonable and available means.
Respondent means a person who has been charged with a violation.
14 C.F.R. §406.103