Is a juvenile court's application of the wrong standard of proof an abuse of discretion?

The juvenile court's application of the wrong standard of proof was an abuse of discretion. "The scope of discretion always resides in the particular law being applied, i.e., in the 'legal principles governing the subject of [the] action . . . .' Action that transgresses the confines of the applicable principles of law is outside the scope of discretion and we call such action an 'abuse' of discretion." (City of Sacramento v. Drew (1989) 207 Cal.App.3d 1287, 1297.) We therefore proceed to a consideration of whether the court's abuse of discretion was prejudicial.