A final judgment or decree rendered in any action brought under RCW 19.86.080 by the state of Washington to the effect that a defendant has violated RCW 19.86.020, 19.86.030, 19.86.040, 19.86.050, or 19.86.060 shall be prima facie evidence against such defendant in any action brought by any party against such defendant under RCW 19.86.090 as to all matters which said judgment or decree would be an estoppel as between the parties thereto: PROVIDED, That this section shall not apply to consent judgments or decrees where the court makes no finding of illegality.