Arizona · Personal injury · Trial-ready representation
Insurers love to argue your prior injury is the real cause of your current pain. Arizona's eggshell-plaintiff rule says the at-fault party still has to pay — and here's how the math actually works.
This is one of the most common defenses we see, and one of the most misunderstood. The other side’s adjuster pulls your medical history, finds an old back injury or a degenerative spine MRI from years ago, and says: “this isn’t from the crash — your back was already bad.” Arizona law has a clear answer to that argument. It usually doesn’t win. But it can absolutely shape the case if you don’t handle it correctly.
The short version
The “eggshell plaintiff” rule is a cornerstone of personal injury law, recognized in Arizona and almost every other state. The idea is simple: the at-fault party doesn’t get to choose their victim. If they injure someone whose body was more vulnerable than average — older, recovering from prior surgery, fragile bones, prior spine problems — the at-fault party is still responsible for all of the resulting harm, even though a different person might have walked away with no injury at all.
The classic phrase: “you take your victim as you find them.” A driver who runs a red light doesn’t get a discount because the person they hit was already managing a back condition.
The most common version of this issue isn’t a brand-new injury at all — it’s an aggravation. The crash made an existing problem worse. Arizona law treats aggravation as compensable damage:
New pain in an old area
If the crash caused new symptoms in a previously asymptomatic prior injury, the at-fault party is responsible for the new symptoms.
Worsening of an active condition
If you were managing a condition and the crash made it worse, the at-fault party is responsible for the worsening.
Acceleration of an inevitable surgery
If you would have eventually needed surgery but the crash made it necessary now, the at-fault party is responsible for moving up that timeline.
Loss of function above your baseline
What matters is the difference between the function you had before the crash and the function you have after.
"It's all degenerative."
Defense radiologists will read your MRI as showing nothing but pre-existing degeneration. The counter is comparison: same imaging from before the crash, plus your treating providers explaining what's actually different.
"You've claimed back pain before."
If you have prior back complaints in the medical record, expect them to come up. The counter is the timeline — you were functional, you were working, the crash changed that.
"You'd have needed surgery anyway."
Even if true, the at-fault party is responsible for the timing. A surgery you would have needed in five years is not the same as a surgery you needed two months after the crash.
"Your prior injury caused the current symptoms."
Causation testimony from treating providers — the people who actually know your case — usually carries more weight than a one-time defense exam.
Disclose your prior history early
To us. Tell us everything. Surprises during depositions are far worse than uncomfortable conversations on day one.
Get the prior records
Old MRIs, prior PT notes, prior surgical reports. They often help by showing you were stable or improving before the crash.
Document your pre-crash baseline
What were you doing the week before the crash? Working, exercising, traveling, lifting your kids? That's the baseline the case will compare to.
Identify witnesses who knew you before
Family, coworkers, friends who can describe what you could do before vs. now.
Tell every treating provider about the crash
So that the medical record makes the connection clear. "Mechanism: MVC on [date]" goes a long way.
Imagine your back was at “60%” function before the crash and is at “30%” function after. The at-fault party isn’t responsible for the original 40% deficit — but they are responsible for the additional 30% deficit and all the medical care, lost work, and pain that goes with it. Arizona law focuses the recovery on what changed, not on what existed before.
That’s a winnable case in almost every situation. It just has to be built honestly, with the prior records in hand and the right experts explaining what the crash actually did.
Free consultation
Every case is different. A short call with a Big Dog Law attorney can answer the question that actually matters for your situation.
