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Negligence in Tort Law: Res Ipsa Loquitur and Negligence Per Se

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Negligence in Tort Law: The Rules of Res Ipsa Loquitur and Negligence Per Se

The four elements central to any negligence case are duty, breach, causation and damages.[1] There are, however, two special negligence law doctrines that assist in proving the first two elements. These are res ipsa loquitur, which allows negligent behavior (which constitutes the duty and breach elements) to be proven based on the surrounding circumstances, and negligence per se, which allows breach to be inferred from the violation of an existing law.

Res Ipsa Loquitur

Res ipsa loquitur, Latin for “the thing speaks for itself,” is a legal theory wherein the facts and circumstances surrounding an injury allow the court to presume that negligence has occurred.[2]  In an ordinary negligence case, the plaintiff must prove that the defendant owed the plaintiff a duty and that his conduct failed to measure up to that duty.[3]  However, under res ipsa loquitur, the defendant’s negligence may be presumed and thus does need not be proven.[4]

The elements of res ipsa loquitur are:

1) the defendant was in exclusive control of the situation or instrument that caused the injury;

2) the injury would not have ordinarily occurred but for the defendant’s negligence; and

3) the plaintiff’s injury was not due to his own action or contribution.[5] 

If these elements are met, the burden shifts to the defendant to show that he was not negligent.[6]   

Res ipsa loquitur typically arises in cases where the negligent act is so obvious that there is no need for evidence of what happened.[7] What must have happened is apparent from the surrounding circumstances. The finder of fact must be able to infer, through common knowledge and experience, that negligence occurred.[8]

For example, in a famous English case, Byrne v. Boadle, a man was walking on a sidewalk outside of a flour warehouse when a barrel of flour fell from a warehouse window.[9] The man did not see the flour fall out of the window, nor could he produce any evidence to indicate how or why the barrel fell from the window of the warehouse. Still, the court thought it apparent that the flour almost certainly came from the flour manufacturer. Moreover, barrels of flour don’t ordinarily fall from warehouse windows in the absence of negligent conduct of the people running that warehouse.[10]  The warehouse workers had exclusive control of the barrel that fell out of the window and the plaintiff’s actions did not contribute to his injury.

Res ipsa loquitur is also sometimes applied in medical malpractice cases where something obviously went wrong in surgery, for example, but precisely what went wrong cannot be proven. A foreign object might have ended up in a patient or suturing may have been proven to be ineffective. While it may not be possible to prove precisely what happened during the surgery, possibly because the only people conscious at the time work for the defendant hospital, events occurred that do not ordinarily occur in the absence of negligence. This is sufficient to swing the burden of proof to the defendant hospital so that it will be held liable unless it can prove the chain of events that demonstrates that it was not negligent.

Negligence Per Se

Negligence per se is applied when conduct that is a violation of a law (whether a criminal statute, ordinance, or administrative order) causes harm.[11] Because violating the law is inherently considered negligent behavior, that the defendant violated the law inherently proves that he breached his responsibility. That his actions caused injury to the plaintiff (in other words, the elements of causation and damages) still must be proven.

To prove negligence per se, the plaintiff must establish that:

(1) there is a statute that defines a certain standard of conduct;

(2) the defendant violated that statute;

(3) the plaintiff is a member of the class that the statute was designed to protect; and

(4) the plaintiff suffered the sort of injury that the statute was designed to prevent.[12]

            Negligence per se is often of use in automobile accident cases. If it can be shown that a driver violated a traffic law in a manner that led to the accident, negligence will be presumed, no matter how slight the violation. So, for example, if a driver drives 35 mph in a 30 mph zone, she is presumed to be negligent, even though it’s quite possible that she was driving no faster than most people on the same road.

 Still, where it can be clearly shown that violating the law was safer under the circumstances than complying, negligence per se may not apply. For example, where state law required that pedestrians walk on sidewalks but where the sidewalks were ice-covered and therefore unsafe, walking on the street instead was not considered negligence per se even though it technically violated the rule.

Moreover, to recover under a theory of negligence per se, the plaintiff must also prove that she was within the class of persons meant to be protected by the statute.[13]  For example, Minnesota’s legislature enacted a law requiring railroad companies to maintain fences at road and street crossings.  An intoxicated man sleeping on the track’s crossing was severely injured when hit by a train. Although the failure to erect a fence at the crossing constituted a violation of Minnesota law, the court concluded that the purpose of the railroad fence law was to keep livestock, domestic animals, and small children off the tracks.  The man, who should have known better than to sleep on a rail bed without the presence of a fence, was not in the class of persons intended to be protected by the law. Therefore, negligence per se could not be used to satisfy the duty and breach elements of a negligence case.[14]       

Additionally, the plaintiff must show that the violated rule was designed to prevent the type of injury that the plaintiff suffered.[15]  In one case, sheep being transported by ship were washed overboard during a storm.  The sheep’s owner sued the owner of the ship for his losses, alleging that the ship owner had broken the law by failing to install pens in which to hold the animals on the journey. Had the pens been installed, he argued, the sheep would have been safe. However, the court observed that the statute's purpose was to prevent infection aboard the ship, not to save the animals from drowning. Because the injury that the plaintiff suffered was not the injury that the statue was designed to prevent, negligence per se could not be invoked. [16]

            Res ipsa loquitur and negligence per se are both doctrines that assist in proving breach of duty in certain negligence cases. The former allows negligence to be inferred from the circumstances and the latter allows it to be inferred from a violation of law. Both have many applications that allow causes of action to go forward where there is a lack of direct evidence proving negligence.


[1] 74 Am. Jur. 2d Torts § 7.

[2] 57B Am. Jur. 2d Negligence § 1163. 

[3] Restatement Second, Torts §§ 281(a), 304.  See also Humble Sand & Gravel, Inc. v. Gomez, 146 S.W.3d 170 (Tex. 2004). 

[4] See Read v. S. Pine Elec. Power Asso., 515 So. 2d 916 (Miss. 1987).

[5] 57B Am. Jur. 2d Negligence § 1164; See also Cooper v. Public Belt R.R., 776 So. 2d 639 (La. Ct. App. 4th Cir. 2000).

[6] 57B Am. Jur. 2d Negligence § 1350. 

[7] 57B Am. Jur. 2d Negligence § 1172.

[8] Hayes v. Peters, 645 S.E.2d 846 (N.C. Ct. App. 2007).

[9] Byrne v. Boadle, 159 Eng. Rep. 299 (1863).

[10] Id.

[11] 57A Am. Jur. 2d Negligence § 685. 

[12] Ullman v. Safeway Ins. Co., 515 So. 2d 916, 919 (D.N.M. 2013).

[13] 57A Am. Jur. 2d Negligence § 730, 735.  

[14] O'Neal v. Burlington N., Inc., 413 N.W.2d 631 (Minn. Ct. App. 1987) where Intoxicated man brought action to recover for injuries sustained when train ran over his left leg while he was sleeping or sitting on the ground next to the railroad tracks with one leg extended across the track.  The Court of Appeals held that man was not within class of persons intended to be protected by statute requiring railroads to build and maintain fences on each side of lines.

[15] 57A Am. Jur. 2d Negligence § 735. 

[16] Gorris v. Scott, 9 L.R.Ex. 125 (1874).