What Is Negligence Per Se In Missouri?

09/16/26

In any personal injury case, the injury victim becomes the plaintiff and has the burden of proof. The evidence must show a breach of the duty of care, typically through negligence. When negligence per se occurs, it acts as a shortcut in a personal injury claim, but what is negligence per se?

what is negligence per se

Under the foundational case law, negligence per se applies when an individual, business, or other entity is found inherently negligent because they violated a safety-related Missouri law, and the law was meant to protect a class of people that includes the injury victim.

Using Negligence Per Se In Missouri Personal Injury and Car Accident Claims

Personal injury law in Missouri and elsewhere is based on the common understanding that people owe a duty of care to those around them and must take reasonable measures to avoid causing harm. Under Missouri’s fault-based injury law of pure comparative negligence, an injury victim must present evidence of the responsible party’s negligence to prove their liability for damages. In typical cases, this requires evidence demonstrating the following legal standards of liability:

  • The responsible party owed a legal duty of reasonable care to the injury victim
  • They violated this duty of care through negligence (negligence may be careless, reckless, or wrongful actions)
  • The violation of duty directly caused the injury
  • The injury victim experienced damages from the injury

Proving the at-fault party’s negligence often requires an in-depth investigation into the accident or incident that caused the injury; however, in a case of negligence per se in Missouri, the injury victim must only prove that the at-fault party violated a safety law meant to prevent the injury victim from harm, and then demonstrate that the injury caused economic and non-economic damages.

Examples of Negligence Per Se In Missouri

The term negligence per se means “negligence in itself,” because the very act is automatically negligent since it’s in violation of a recognized state or federal safety law. Common examples include the following:

  • When a driver intentionally runs through a red light, it’s a violation of the law, and the law is meant to protect those drivers with the right of way in an intersection
  • Driving while intoxicated or over the legal blood alcohol concentration (BAC) is a violation of Missouri’s law, and the law is meant to protect other drivers sharing the road
  • When an apartment building owner violates a building code or safety code, such as failing to install a handrail on a staircase, and a tenant suffers injury in a fall, it’s negligence per se
  • If a trucking company fails to enforce FMCSA regulations limiting a driver’s hours of service, resulting in a drowsy driving accident that causes harm to a motorist, it’s a violation of a federal safety regulation meant to protect motorists sharing the road with commercial vehicles

While cases of negligence per se can make it easier for an injury victim to prove their case, they must still meet the burden of proof in showing that the at-fault party violated a law, the law was meant to protect a class of people that includes the injury victim, and that the injury victim suffered damages from the violation.

Common Defenses to Negligence Per Se

The liable party often mounts common defense strategies in Missouri negligence per se cases, such as claiming that an emergency prevented the responsible party from complying with the statute, that complying with the statute would have endangered the responsible party, or that any reasonable person would have violated the law under the same circumstances. An experienced accident attorney protects their client’s right to recover the full value of their damages in negligence per se cases.