How a pre-existing medical condition affects your personal injury settlement

CDC data puts diagnosed arthritis at 53.2 million American adults and another 51.6 million live with chronic pain. Which means the average person walking away from a crash almost certainly has a chart with something in it about a back, a neck, or a knee.

Insurers work that angle. One mention of pain in the same body part anywhere in your history and the conversation shifts: it’s your age, your job, your old injury, anything but their insured driver. The law reads it differently. Here’s what you are actually owed.

Can you still sue if you had a pre-existing condition

A personal injury claim with a pre-existing condition runs on the same rules as any other one because American tort law rests on the eggshell plaintiff rule, also called the thin skull doctrine. The wrongdoer takes the injured person as they find them. Cornell Law School puts it this way: the defendant answers for the full extent of the harm, even when the victim’s reaction was unusual and impossible to predict.

The rule goes back further than the car itself. In Vosburg v. Putney (Wisconsin, 1891), a schoolboy gave a classmate a light kick in the shin, not knowing the leg was already hurt. That kick turned into an infection, two surgeries and a permanent limp. He paid for all of it. A careless driver carries the same risk because the person in the next car may be more fragile than average.

Aggravation vs. new injury: the key legal distinction

You don’t get paid for the illness you carried into the crash. You get paid for how much worse it got. California’s jury instruction CACI 3927 says a plaintiff recovers nothing for a condition that existed beforehand, but when the defendant’s conduct made it worse, the jury must compensate the worsening. Georgia’s instruction 66,504 adds the detail that decides a lot of cases: a dormant condition, one that never announced itself before the wreck, gets the same protection as an obvious diagnosis. Arizona’s RAJI borrows the California language almost word for word.

So the argument moves out of law and into medicine. Whoever can document how the person functioned before the incident and what changed after wins it.

How insurance companies use pre-existing conditions to deny or lowball claims

Carriers have learned to build a whole defense around an old diagnosis and a pre-existing conditions personal injury case usually meets the same three tactics:

1. Every current symptom gets recast as the old problem continuing, with the crash written off as coincidence.
2. A demand for medical records going back years. The “standard” release they hand you in week one usually carries no time limit and no body-part limit, so the adjuster gets your whole file and hunts for any mention of pain in the right place.
3. A pointer to degenerative findings on imaging.

That last one sounds authoritative right up until somebody checks it. The review by Brinjikji and colleagues (AJNR, 2015) pooled data on 3,110 people who had never complained of back pain: disc degeneration turned up in 37% of 20-year-olds and 96% of 80-year-olds. More than half of people in their thirties carry that wear and never feel a thing. So a degenerative disc disease injury claim doesn’t die on the radiology report, since the scan alone can’t explain why the pain started the day after impact.

The valuation often isn’t done by a person, either. Allstate and other carriers run Colossus, software that converts records into codes and produces a payout range, docking value for every prior condition. In 2010 Allstate paid $10 million to settle with regulators in 45 states after a review found the program was tuned inconsistently.

What evidence proves your injury was aggravated, not pre-existing

Medical records in a personal injury claim are only as good as the contrast they draw. Those baseline files set the starting line: how often you saw a doctor before the crash, whether you were treating at all and whether work came with restrictions. Your treating physician ties the worsening to the specific incident and the wording matters since courts want an opinion held to a reasonable degree of medical probability. Imaging from before and after shows what words can’t.

Then come the witnesses nobody can hire. A spouse, a foreman, the guy you played tennis with on Saturdays remember who you were in March and see who you are in May. That testimony often outweighs two paid experts arguing.

The defense can’t simply float the idea that an old injury explains everything. California has enforced Evidence Code § 801.1 since 2024. A defense expert naming an alternative cause has to meet the same standard of proof the plaintiff’s expert does.

How a pre-existing condition affects settlement value

What’s recoverable is the increment, not the whole condition. Say you lived with a nagging lower back and picked up a physical therapy referral once a year, then had surgery after the crash and lost six months of work. In a personal injury claim with a pre-existing condition, that gap is the entire fight. Treatment bills and lost earnings go in first. So does the pain and suffering a pre-existing condition produces once someone else has made it worse.

The adjuster’s first number is almost always low and the reason given is that some of the pain was there before. Courts see it differently. In October 2024 the Georgia Court of Appeals upheld a $15 million verdict in Geary v. Estate of Tapley, where the 80-year-old patient had congestive heart failure, COPD and emphysema and the defense built its case on exactly that. Jurors were instructed that a defendant takes the plaintiff as he finds him, which is what makes the aggravation of a pre-existing injury compensable at full value.

Why disclosing your full medical history to your attorney protects your case

Hiding the past accomplishes nothing. The file arrives by subpoena anyway and the detail you forgot surfaces at a deposition at the worst possible moment to explain it. A lawyer who has the history from day one gets ahead of it: securing a causation opinion from your treating doctor, narrowing the records request to what actually relates to the case and prepping you for questions about the old diagnosis.

Kermani LLP works on contingency, so the fee comes out of the recovery and nothing else. The firm’s personal injury lawyers have returned more than $100 million to clients, including cases where the insurer called it old news from the first phone call. You can run the numbers yourself first, since a personal injury settlement calculator gives you a rough range, though only a review of your medical history shows what the claim is really worth. The consultation is free.

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