A final judgment or decree rendered in any civil or criminal proceeding brought by the Attorney General under this chapter to the effect that a defendant has violated this chapter shall be prima facie evidence against such defendant in any action for damages brought by any other party against such defendant under subparagraph (2) of section 1507 of this chapter, as to all matters respecting which said judgment or decree would be an estoppel as between the parties thereto; provided, that this section shall not apply to civil consent judgment or decrees entered before any testimony has been taken.