46 U.S.C. § 12140

1. (a)The Secretary may conduct investigations and inspections regarding compliance with this chapter and regulations prescribed under this chapter.
2. (b)
   1. (1)For the purposes of any investigation conducted under this section, the Secretary may issue a subpoena to require the attendance of a witness or the production of documents or other evidence relevant to the matter under investigation if—
      1. (A)before the issuance of the subpoena, the Secretary requests a determination by the Attorney General as to whether the subpoena—
         1. (i)is reasonable; and
         2. (ii)will interfere with a criminal investigation; and
      2. (B)the Attorney General—
         1. (i)determines that the subpoena is reasonable and will not interfere with a criminal investigation; or
         2. (ii)fails to make a determination with respect to the subpoena before the date that is 30 days after the date on which the Secretary makes a request under subparagraph (A) with respect to the subpoena.
   2. (2)In the case of a refusal to obey a subpoena issued to any person under this section, the Secretary may invoke the aid of the appropriate district court of the United States to compel compliance.