own life. "The first duty in an emergency is to one's own self, as long as that person did not contribute to or cause the emergency." (Emergency Doctrine.) Negligence per se When a statute, which is designed to protect the public, is violated while performing an allegedly negligent act, a court may adopt the statute as establishing the standard of care for tort liability. This is negligence per se. There is no negligence per se doctrine in federal law. Four elements are deemed necessary for a statute to apply in a negligence case. First the person harmed must be a member of the class of persons which the law was intended to protect. Second, the danger or harm must be one that the law was intended to prevent. Thirdly, there must be some causal relationship established between the breach of the statute and the harm caused. Fourthly, the criminal statute must be concrete, specific and measurable enough to clearly establish a standard of breach. Courts are reluctant to create new torts out of criminal statutes. (See Restatement (Second) of Torts, sections 297, 288.) However, there are five valid excuses that are available for a defendant to defeat a standard of negligence per se. (Restatement (Second) of Torts section 288.1(2).) First, the defendant may not know of the breach due to incompetence. Secondly, he might either lack knowledge or reason to know of the breach or duty. Furthermore, for some explainable reason, he may be unable to comply, despite diligence. The breach may be due to a sudden emergency not of one's own making. And lastly, in special situations it may be safer to not comply than to comply. In cases where these defenses are applied, negligence per se doctrine creates no more than a rebuttable presumption of negligence that shifts the burden of proof from the plaintiff to the defendant. Reasonable person/ordinary care In balancing risks to establish a reasonable person's standard of ordinary care, the calculus of negligence establishes that the probability of the harm potentially caused (P) must be balanced along with the gravity of the harm which could result (G), against the burden of conforming to a new and less dangerous course of action (B) along with the utility of maintaining the same course of action as it was (U). This is sometimes noted in shorthand as P+G v. B+U, deriving from a formulation expressed by Judge