Eggshell Skull Doctrine | How Does it Affect Personal Injury Settlement

It’s a low-speed crash. Many people might walk away with a stiff neck or a headache. But not everyone is the same. You may have a preexisting condition, such as degenerative disc disease, or you may still be recovering from a prior surgery. For you, the impact doesn’t just cause discomfort; it leads to a hospital visit.

Then the other driver’s insurance company calls. They suggest they aren’t responsible for your medical bills because your back was “already injured,” arguing that a typical person would not have been hurt this seriously.

That is misleading. They are hoping you don’t know the law. Under the Eggshell Skull Doctrine, the law recognizes that a person who causes an accident is responsible for the full extent of the injuries they cause, even if the injured person was more vulnerable than average.

Key Takeaways

• You don’t have to be perfect. The law protects victims even if they have pre-existing conditions or are unusually fragile compared to the average person.
• The defendant pays for the result, not the expectation. It does not matter if a “normal” person would have been fine. If the defendant’s negligence triggered your injury, they are liable for the full outcome.
• Aggravation is compensable. You can collect damages if an accident “lights up” or worsens a dormant condition that wasn’t bothering you before.
• Mental health counts too. This doctrine applies to psychological conditions, meaning you can recover damages if a crash triggers a relapse of a mental health issue.

What Is the Eggshell Skull Doctrine?

Imagine a person with a skull as thin as an eggshell. If you walk by and tap them on the head, you might think you’re just being annoying. But because their skull is fragile, that little tap fractures it and kills them.

You can’t go to court and say, “Well, I only tapped him. A normal person would have been fine.” The court will tell you that you take your victim as you find them. If you choose to act negligently, you own the consequences. All of them.

This isn’t just a theory. It comes from a real case called Vosburg v. Putney from 1891. A schoolboy kicked another student in the shin. It was a light kick. But the victim had a previous infection in that leg. The kick aggravated it, and the boy eventually lost the use of his leg. The court made the kicker pay for the leg, establishing the rule that the wrongdoer is liable for the actual injury caused.

Does a Pre-Existing Condition Ruin My Personal Injury Claim?

No. In fact, most people have some kind of history. About 6 in 10 US adults live with a chronic disease. If the law only protected people with perfect health, almost no one could sue for injuries.

Insurance adjusters love to argue that your injury is “pre-existing.” They see a note in your medical file about back pain from 2018 and try to deny your claim for a crash in 2024.

The law stops them from doing this. California jury instructions, for example, explicitly state that a plaintiff is entitled to full damages for any worsening of a condition caused by the defendant. The jury is told they must award damages even if a normally healthy person would not have suffered a similar injury.

The keyword here is aggravation.

If your back was at a pain level of 2 before the crash, and the crash pushed it to a 9, the driver is responsible for that difference. They are responsible for the change in your quality of life.

How Does the Law Distinguish Between New Injuries and Old Ones?

This is where things get technical. You have to prove the accident was the “straw that broke the camel’s back.”

Courts look at whether the accident was a “precipitating factor.” In a famous case called Benn v. Thomas, a man with a history of coronary disease died of a heart attack six days after a minor car accident. The defense argued the car crash was too small to kill him. The court disagreed. They ruled that the driver was liable for the death because the accident triggered the fatal event. The “eggshell” in this case was the man’s heart.

The law asks a simple question: Would this specific injury have happened right now if the accident hadn’t occurred?

If the answer is no, then the defendant is on the hook.

What Is the Difference Between Eggshell Skull and Crumbling Skull?

There is one major exception you need to know about. Defense lawyers will try to pivot from the “Eggshell Skull” to the “Crumbling Skull” defense.

Here is the difference:

The Eggshell Plaintiff is stable. They have a condition, but they are managing it. They might be fragile, but they are holding it together. The accident comes along and breaks them. The defendant pays for everything.

The Crumbling Skull Plaintiff is already deteriorating. Their condition is active and getting worse on its own. The defense will argue that your pain was inevitable. They will cite cases like Maurer v. United States, arguing they should only pay for the temporary aggravation of a condition that was going to disable you anyway.

Think of it like a timeline.

• Eggshell: You were fine for the next 10 years. The crash ruined that. (Full Payout)
• Crumbling: You were going to need surgery next month anyway. The crash just made you need it today. (Limited Payout)

Your lawyer’s job is to prove you were stable before the crash.

Can I Claim Damages for Mental Health Under This Rule?

Yes. The doctrine applies to your mind just as much as your bones. Courts recognize the “Eggshell Psyche.”

If you have a history of depression, PTSD, or schizophrenia that was in remission, and the stress of a car accident brings it back, the other driver is liable.

In Bartolone v. Jeckovich, a bodybuilder with a history of schizophrenia was involved in a minor crash. The physical injuries were small, but the stress caused a total mental breakdown. The court found that because the accident precipitated the psychological condition, the defendant had to pay for the mental health treatment and disability.

How Do I Prove the Accident Aggravated My Injury?

You cannot just tell the insurance adjuster you feel worse. You need proof.

The biggest weapon in these cases is your medical imaging, but maybe not in the way you think. Insurance companies love to point at an MRI showing “degenerative disc disease” and say it proves you were already hurt.

But medical science says otherwise. Studies show that 37% of 20-year-olds have disc degeneration with zero pain. By age 80, that number hits 96% of people.

Having a “bad MRI” doesn’t mean you were in pain. It just means you had a condition. If you can show medical records proving you were asymptomatic (symptom-free) before the crash, and in severe pain after, that gap proves the aggravation.

You also need witnesses. Friends, family, and coworkers who can testify: “He used to play basketball every Saturday before the crash. Now he can’t even sit in a chair for an hour.” That testimony bridges the gap between the medical charts and real life.

Why You Need a Strategy

The Eggshell Skull Doctrine is powerful. It stops bullies from escaping liability. But it is not automatic.

The other side will dig through your entire medical history. They will look for every doctor’s visit you’ve ever had to prove you are a “Crumbling Skull” case rather than an “Eggshell” case. They want to show your injury was inevitable.

You need to build a wall of evidence that shows your life was stable before they crashed into it. The law says they have to take you as they find you. Make sure they pay for your damages.

Call us or contact us online to talk through your case.