Most personal injury claims are based on a theory of negligence. To determine who is at fault, the law requires that the plaintiff prove that there was a duty of care owed by the defendant to the plaintiff, that the duty was breached, that the breach was the cause of the injury, and that actual injury occurred. Unlike a criminal case where the prosecution must prove its case beyond a reasonable doubt, in a civil tort action like negligence, the plaintiff must only prove its case with a preponderance of the evidence.