; or (3) has testified, or is about to testify, in any inquiry or proceeding relating to any right provided under this title. 205. Remedies and enforcement (a) Investigative authority (1) In general To ensure compliance with this title, including any regulation or order issued under this title, the Secretary shall have, subject to paragraph (3), the investigative authority provided under section 11(a) of the Fair Labor Standards Act of 1938 ( 29 U.S.C. 211(a) ). (2) Obligation to keep and preserve records (A) In general Each employer shall maintain for a period of not less than 3 years, or for the duration of any claim (including the duration of a related civil action or investigation) pending pursuant to this title, whichever is longer, all records necessary to demonstrate compliance with this title, including compliance with the requirements of regulations issued by the Secretary under section 206. Such records shall include documentation of offers of hours of work to employees and responses to such offers. (B) Copies Each employer shall, upon a reasonable request of an employee of the employer, provide the employee with a copy of the records described in subparagraph (A) relating to the employee. (3) Required submissions generally limited to an annual basis The Secretary shall not require, under the authority of this subsection, any employer to submit to the Secretary any books or records more than once during any 12-month period, unless the Secretary has reasonable cause to believe there may exist a violation of this title, including any regulation or order issued pursuant to this title, or is investigating a charge pursuant to subsection (c). (4) Subpoena powers For the purposes of any investigation provided for in this subsection, the Secretary shall have the subpoena authority provided for under section 9 of the Fair Labor Standards Act of 1938 ( 29 U.S.C. 209 ). (b) Civil action by employees (1) Liability (A) In general Any employer who violates section 202, 203, or 204 (each such provision referred to in