By Chris Carter — Managing Solicitor, Carter & Carter Solicitors · March 2026

Most people who have a pre-existing condition assume it rules them out. A bad back they’ve managed for years. A joint problem that’s been there since a previous injury. A stress disorder that was already on their medical record. They’re hurt at work, and the first thought isn’t “do I have a claim” — it’s “they’ll just say it was already there.”

We hear this almost every week. And almost every week, we have to explain the same thing: that’s not how the law works.

The law doesn’t ask whether you were healthy before the accident. It asks whether your employer kept you safe. If they didn’t — and if that failure made your existing condition worse — they are liable for that worsening. Where your health started is their problem to work around. Not yours.

What Does “Pre-Existing Condition” Actually Mean in a Compensation Claim?

It covers a wider range than most people expect. A bad back that was manageable — uncomfortable on bad days, but not stopping you working. A knee that never quite healed after an old injury. Anxiety that was under control. A joint condition that wasn’t yet causing real problems. All of these count.

We speak to people in exactly this position almost every week. They’ve been hurt at work. Something that was already there has been made worse. And they’ve convinced themselves the two things cancel each other out. They don’t.

The right question isn’t “were you perfectly healthy before?” It’s simpler: did the accident leave you worse off than you were? If yes — and if your employer was responsible for that accident — the claim is about the difference. That’s what compensation is for.

What Is the Thin Skull Rule — and Why Does It Protect You?

The thin skull rule is one of the most important principles in English tort law. It says, simply, that a defendant must take their victim as they find them.

Think of it this way. If an employer’s negligence causes a minor burn to a worker who turns out to have an underlying condition that makes the outcome far worse, the employer can’t turn around and say “we didn’t know about the condition.” They caused the harm. They’re responsible for all of it. This principle was established in Smith v Leech Brain & Co Ltd [1962] and it hasn’t changed. You take your victim as you find them — vulnerable or otherwise.

What Kinds of Pre-Existing Conditions Come Up in These Claims?

In workplace injury claims, we commonly see bad backs, joint problems and shoulder injuries that were manageable before an accident — then weren’t. In needlestick injury claims, it’s often anxiety or OCD-type health anxiety that already existed but was sent into a completely different gear by the trauma and the months of waiting for blood test results. Both are valid claims.

There’s also a category worth knowing about. Sometimes a condition was already going to get worse eventually — but the accident brought that deterioration forward by years. Compensation in those cases covers the period that was pulled forward: the health problems you experienced sooner than you otherwise would have. It’s a more limited claim, but it’s real, and it matters.

The thing that makes or breaks these cases is nearly always the same: a clear picture of where things were before the accident, and where they ended up after it. Stable before, significantly worse after — that’s the story the evidence needs to tell.

What Should You Do Right Now?

If the accident is recent — report it. See a doctor. Tell them clearly what happened and what has changed since. That medical record is going to matter.

If the accident was weeks or months ago and you didn’t report it at the time — don’t assume that rules you out. It doesn’t automatically. Ring us and we’ll tell you honestly where things stand.

Either way, don’t rule yourself out before you’ve spoken to someone. That’s what we’re here for.

How Do We Handle Pre-Existing Condition Claims at Carter & Carter?

There are just two of us at Carter & Carter — me and David Healey. No juniors. No case handlers. Every person who rings us speaks to a qualified solicitor from the first call to the last.

We won’t tell you what you want to hear to get you through the door. If we think you have a claim, we’ll say so — and explain exactly how the pre-existing condition fits into the picture. If we don’t think you have one, we’ll tell you that too. Honestly. That’s how we’ve built 249 five-star reviews over nearly two decades.

The call is free. There’s no obligation. And the time limit for personal injury claims is three years from the date of the accident — so don’t sit on this.