Understanding “Intervening” and “Superseding” Causes in a Personal Injury Case

When could bad luck, an act of nature, or a third party’s carelessness derail your personal injury claim?

Updated by , J.D., University of San Francisco School of Law
Updated by Charles Crain, Attorney (UC Berkeley School of Law)

To win a personal injury case you must prove that you suffered losses caused by someone else's negligence (in other words, their carelessness). Sometimes this is straightforward. If a driver isn't paying attention, runs a stop sign, and hits your vehicle, it probably won't be difficult to assign full responsibility for the crash to that negligent driver.

But what about situations where the chain of events is more complicated? Accidents can have multiple causes, and sometimes it's hard to tell if an injury came about as a result of negligence or just bad luck.

A plaintiff in a personal injury case has to be able to establish a so-called "causal chain" linking their injury to the negligence of the defendant. But when the action of a third party, or even an act of nature, plays a role in your accident it sometimes breaks that chain—and can diminish or even wipe out the defendant's liability.

In these kinds of cases it's important to understand what insurance adjusters and lawyers mean when they talk about "intervening" and "superseding" causes.

How Does an Intervening Cause Affect a Personal Injury Case?

An "intervening cause" is something that:

  • occurs after the defendant's negligent action (or inaction), and
  • contributes to or worsens the plaintiff's injury.

An intervening cause could be the action of another person (who is generally called a "third party"), or it could be an act of nature, such as a branch falling from a tree or a weather-related event.

An intervening cause doesn't necessarily relieve a defendant of responsibility for a plaintiff's injuries. For example, let's say the Acme Bus Company decides to use a busy parking lot as a drop-off point for its passengers. When Pablo steps off the bus, Ingrid (who is texting instead of focusing on driving) hits him with her car. Pablo files a personal injury lawsuit against Acme for failing to provide a safe place for passengers to disembark.

In this situation, Ingrid's actions would be an intervening cause of Pablo's injuries—if she'd been more careful she could have stopped before hitting Pablo. But that doesn't mean that Acme is automatically off the hook. A jury could still find the company liable for choosing an unsafe location for dropping off passengers.

Learn more about how the law works when multiple people's negligence contributes to a defendant's injuries.

What's the Difference Between an Intervening Cause and a Superseding Cause?

What separates an intervening cause from a superseding cause is foreseeability. An intervening cause will be called a superseding cause (or act), and relieve the original defendant of liability, if the intervening act was or should have been reasonably foreseeable to the original defendant.

Let's go back to our example of Pedro, Ingrid, and Acme Bus Company. Pedro would have a good argument, based on foreseeability, that Acme shares some of the blame for the injuries he suffered when Ingrid hit him with her car. When you make people exit a bus into a busy parking lot, it's foreseeable that someone might get hit by a distracted driver.

On the other hand, let's say Pedro steps off the bus into the parking lot on a clear day and is struck by lightning. Here, the lightning strike is a superseding act that relieves Acme Bus Company of responsibility for Pedro's injuries. Acme negligently used a dangerous drop-off location, but being struck by lightning isn't a foreseeable consequence of that kind of negligence.

Read More About What Makes a Successful Personal Injury Case

Superseding causes are just one of the issues that could come up if you're trying to show that someone is legally responsible for your injuries. You can learn more about proving fault in a personal injury case, and about what goes into establishing your damages so you can receive fair compensation for your injuries. If you've been in an accident and are considering consulting an attorney, make sure you know what to ask so you can find the best lawyer for your situation.

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