What is the test for determining whether a defendant is liable for injuries sustained by a plaintiff as a result of negligence?

injury, so that 'but for' the defendant's negligence the injury would not have been sustained." Akins v. County of Sonoma, 67 Cal. 2d 185, 198-199 (1967)(citations omitted). Additionally, in cases involving a later cause of independent origin, courts should consider "whether the later cause of independent origin, commonly referred to as an intervening cause, was foreseeable by the defendant or, if not foreseeable, whether it caused injury of a type which was foreseeable. If either of these questions is answered in the affirmative, then the defendant is not relieved from liability towards the plaintiff; if, however, it is determined that the intervening cause was not foreseeable and that the results which it caused were not foreseeable, then the intervening cause becomes a supervening cause and the defendant is relieved from liability for the plaintiff's injuries." Id.