(a) Liability of employer
No employer shall be subject to any liability or punishment under the Fair Labor Standards Act of 1938, as amended [29 U.S.C. 201 et seq.] the Walsh-Healey Act, or the Bacon-Davis Act ¹ (in any action or proceeding commenced prior to or on or after May 14, 1947), on account of the failure of such employer to pay an employee minimum wages, or to pay an employee overtime compensation, for or on account of any activity of an employee engaged in prior to May 14, 1947, except an activity which was compensable by either—

(1) an express provision of a written or nonwritten contract in effect, at the time of such activity, between such employee, his agent, or collective-bargaining representative and his employer; or

(2) a custom or practice in effect, at the time of such activity, at the establishment or other place where such employee was employed, covering such activity, not inconsistent with a written or nonwritten contract, in effect at the time of such activity, between such employee, his agent, or collective-bargaining representative and his employer.

(b) Compensable activity
For the purposes of subsection (a), an activity shall be considered as compensable under such contract provision or such custom or practice only when it was engaged in during the portion of the day with respect to which it was so made compensable.

(c) Time of employment
In the application of the minimum wage and overtime compensation provisions of the Fair Labor Standards Act of 1938, as amended [29 U.S.C. 201 et seq.], of the Walsh-Healey Act, or of the Bacon-Davis Act,¹ in determining the time for which an employer employed an employee there shall be counted all that time, but only that time, during which the employee engaged in activities which were compensable within the meaning of subsections (a) and (b) of this section.

(d) Jurisdiction
No court of the United States, of any State, Territory, or possession of the United States, or of the District of Columbia, shall have jurisdiction of any action or proceeding, whether instituted prior to or on or after May 14, 1947, to enforce liability or impose punishment for or on account of the failure of the employer to pay minimum wages or overtime compensation under the Fair Labor Standards Act of 1938, as amended [29 U.S.C. 201 et seq.], under the Walsh-Healey Act, or under the Bacon-Davis Act,¹ to the extent that such action or proceeding seeks to enforce any liability or impose any punishment with respect to an activity which was not compensable under subsections (a) and (b) of this section.

(e) Assignment of actions
No cause of action based on unpaid minimum wages, unpaid overtime compensation, or liquidated damages, under the Fair Labor Standards Act of 1938, as amended [29 U.S.C. 201 et seq.], the Walsh-Healey Act, or the Bacon-Davis Act,¹ which accrued prior to May 14, 1947, or any interest in such cause of action, shall hereafter be assignable, in whole or in part, to the extent that such cause of action is based on an activity which was not compensable within the meaning of subsections (a) and (b).