What is the test for reducing the amount of restitution at a personal injury restitution hearing?

Prior to the restitution hearing, the defense argued that the amount of restitution should be reduced under the comparative negligence doctrine pursuant to People v. Millard (2009) 175 Cal.App.4th 7, 95 Cal.Rptr.3d 751 (Millard ). The trial court identified the issues here as whether the comparative negligence doctrine applied in Millard is applicable when a deceased victim's family is seeking restitution rather than the victim, and whether factually, the victim's negligence was a "substantial factor" in causing the economic loss.