What is the Difference Between Negligence and Negligence Per Se?

Most personal injury claims are based on negligence. Negligence is a legal term that means something similar to “carelessness.” In the event of an injury caused by another person, you must prove that person was negligent in order to receive compensation. “Negligence per se” is a legal concept that provides you with an easier way to prove negligence under certain circumstances.

What is Negligence?

Put briefly, negligence is the failure to exercise the degree of care that a hypothetical “reasonable person” would have exercised. Exactly how much care is “reasonable” varies according to the circumstances. This is often a key issue in a personal injury case. 

Does the removal of a “Wet Floor” sign five minutes after mopping a grocery store floor constitute negligence? Does driving one mph under the speed limit during an ice storm constitute negligence?  The answer is not always obvious.

Evidence of Negligence

There are many possible forms of evidence to support a negligence, claim, including:

  • Physical evidence;
  • Scientific evidence; 
  • Demonstrative evidence such as graphs and charts;  
  • Investigation reports; 
  • Expert witness testimony; and
  • Eyewitness accounts.

In many cases, the determination of negligence is a judgment call that requires the jury to evaluate the defendant’s actions. Since different juries may look at the same evidence and reach contradictory conclusions, the ambiguous nature of the term “negligence” adds significant uncertainty to a negligence claim.

What is Negligence Per Se?

Negligence per se refers to a finding of negligence based solely on the violation of a particular kind of legal standard. Such legal standards include:

  • Traffic laws;
  • Trucking regulations (requiring break periods every so often so that the driver will not fall asleep at the wheel, for example);
  • Blood alcohol content limits (the 0.08% standard for DUI, for example);
  • Consumer product standards;
  • Building codes; and
  • Other legally binding safety rules.

The point is that as long as the defendant violated a safety law that was designed to prevent the type of harm that actually occurred, and the victim is the sort of person the statute was designed to protect, the defendant was almost certainly negligent. With negligence per se, you don’t need to weigh the circumstances to determine what a “reasonable person” would have done. The defendant broke the law; therefore, the defendant was negligent. This principle makes it easier for you to win your claim.

The Use of Negligence Per Se By the Defendant Instead of the Accident Victim

When more than one party is at fault for an injury, Pennsylvania applies a ”modified comparative fault” system to apportion damages among at-fault parties. A defendant can reduce or even eliminate their liability by proving that the accident victim was mostly (i.e., 51% or more) at fault for their own injuries. Such a defendant might seek to establish that the opposing party was negligent under the negligence per se principles described above.

Beyond Negligence: What Else Must You Prove to Win?

Proving that the opposing party owed a duty of care and proving that that duty of care was breached is not enough to win. You need to prove two more legal elements to establish liability: damages and causation. 


“Damages” is a legal term that simply refers to losses. These losses can be economic losses such as medical bills, lost earnings, or child care expenses while you’re in the hospital. They can also refer to non-economic losses such as pain and suffering and mental anguish. In rare cases, you might even win punitive damages. In any case, you must prove the damages you are claiming with admissible evidence. This is a requirement even if the defendant was negligent. There have even been personal injury cases in which courts have found defendants liable, but awarded the victim only one dollar in damages.


The final legal element of a personal injury claim that you must prove is causation. You must prove that the defendant’s actions were the actual and proximate cause of your injury. Suppose, for example, that you suffered a car accident injury that the defendant caused by running a stoplight. Suppose further that your damages claim includes a large amount for the serious back injury you suffer from.

Even if the defendant was clearly negligent, they can still avoid liability if they can prove that your back injury was actually an old occupational injury that predated your car accident. To establish liability, you will need to show a causal connection between the defendant’s actions and your losses.

If you suffered a significant personal injury that someone else might be liable for, you need the resources of an experienced personal injury lawyer in Chambersburg. And your claim might be worth a lot more than you think it is.