; and (B) need not allege facts tending to exclude the possibility of independent action. (b) Civil actions by injured persons (1) Civil action authorized Any person who is aggrieved by a violation of this Act may bring a civil action in an appropriate district court of the United States, without respect to the amount in controversy, to recover an amount described in paragraph (2). (2) Award amount (A) In general The court shall award to the plaintiff threefold the damages sustained by the plaintiff and the reasonable cost of litigation, including a reasonable attorney fee. (B) Interest on damages Pursuant to a motion by the plaintiff promptly made, the court may award simple interest on actual damages sustained by the plaintiff for the period beginning on the date of service of the pleading of the plaintiff setting forth a claim under this Act and ending on the date of judgment, or for any shorter period therein. (3) Invalidity of pre-dispute arbitration agreements and pre-dispute joint action waivers At the election of the plaintiff in an action authorized under paragraph (1), a pre-dispute arbitration agreement or pre-dispute joint action waiver relating to a violation of this Act shall be invalid or unenforceable. 5. Relationship to State and local laws Nothing in this Act may be construed to preempt any State, Tribal, city, or local law, regulation, or ordinance that explicitly supplements this Act. 6. Severability If any provision of this Act, or the application of such a provision to any person or circumstance, is held to be unconstitutional, the remaining provisions of this Act, and the application of such provisions to any person or circumstance shall not be affected thereby.