49 U.S.C. § 502: General authority

The Secretary of Transportation shall carry out this chapter. inquire into and report on the management of the business of rail carriers and motor carriers; inquire into and report on the management of the business of a person controlling, controlled by, or under common control with those carriers to the extent that the business of the person is related to the management of the business of that carrier; and obtain from those carriers and persons information the Secretary determines to be necessary. confer and hold joint hearings with State authorities; cooperate with and use the services, records, and facilities of State authorities; and make cooperative agreements with a State to enforce the safety laws and regulations of a State and the United States related to highway transportation. The Secretary may subpena witnesses and records related to a proceeding or investigation under this chapter from a place in the United States to the designated place of the proceeding or investigation. If a witness disobeys a subpena, the Secretary, or a party to a proceeding or investigation before the Secretary, may petition the district court for the judicial district in which the proceeding or investigation is conducted to enforce the subpena. The court may punish a refusal to obey an order of the court to comply with a subpena as a contempt of court. In a proceeding or investigation, the Secretary may take testimony of a witness by deposition and may order the witness to produce records. A party to a proceeding or investigation pending before the Secretary may take the testimony of a witness by deposition and may require the witness to produce records at any time after a proceeding or investigation is at issue on petition and answer. If a witness fails to be deposed or to produce records under this subsection, the Secretary may subpena the witness to take a deposition, produce the records, or both. A deposition may be taken before a judge of a court of the United States, a United States magistrate judge, a clerk of a district court, or a chancellor, justice, or judge of a supreme or superior court, mayor or chief magistrate of a city, judge of a county court, or court of common pleas of any State, or a notary public who is not counsel or attorney of a party or interested in the proceeding or investigation. Before taking a deposition, reasonable notice must be given in writing by the party or the attorney of that party proposing to take a deposition to the opposing party or the attorney of record of that party, whoever is nearest. The notice shall state the name of the witness and the time and place of taking the deposition. The testimony of a person deposed under this subsection shall be taken under oath. The person taking the deposition shall prepare, or cause to be prepared, a transcript of the testimony taken. The transcript shall be subscribed by the deponent. The testimony of a witness who is in a foreign country may be taken by deposition before an officer or person designated by the Secretary or agreed on by the parties by written stipulation filed with the Secretary. The deposition shall be filed with the Secretary promptly. Each witness summoned before the Secretary or whose deposition is taken under this section and the individual taking the deposition are entitled to the same fees and mileage paid for those services in the courts of the United States.