When civil actions involving one or more common questions of fact are pending in different districts, such actions may be transferred to any district for coordinated or consolidated pretrial proceedings. Such transfers shall be made by the judicial panel on multidistrict litigation authorized by this section upon its determination that transfers for such proceedings will be for the convenience of parties and witnesses and will promote the just and efficient conduct of such actions. Each action so transferred shall be remanded by the panel at or before the conclusion of such pretrial proceedings to the district from which it was transferred unless it shall have been previously terminated: Provided, however, That the panel may separate any claim, cross-claim, counter-claim, or third-party claim and remand any of such claims before the remainder of the action is remanded.

Such coordinated or consolidated pretrial proceedings shall be conducted by a judge or judges to whom such actions are assigned by the judicial panel on multidistrict litigation. For this purpose, upon request of the panel, a circuit judge or a district judge may be designated and assigned temporarily for service in the transferee district by the Chief Justice of the United States or the chief judge of the circuit, as may be required, in accordance with the provisions of chapter 13 of this title. With the consent of the transferee district court, such actions may be assigned by the panel to a judge or judges of such district. The judge or judges to whom such actions are assigned, the members of the judicial panel on multidistrict litigation, and other circuit and district judges designated when needed by the panel may exercise the powers of a district judge in any district for the purpose of conducting pretrial depositions in such coordinated or consolidated pretrial proceedings.