Upon motion, a court may award attorneys' fees to a successful party against one or more opposing parties in any action which has resulted in the enforcement of an important right affecting the public interest if:
Attorneys' fees awarded to a public entity pursuant to this section shall not be increased or decreased by a multiplier based upon extrinsic circumstances, as discussed in Serrano v. Priest, 20 Cal. 3d 25, 49.
Ca. Civ. Proc. Code § 1021.5