If you were injured on the job but already had a medical issue—like an old back injury or chronic illness—you may worry your workers’ compensation claim will be denied. But under California law, having a pre-existing condition does NOT automatically disqualify you.
In fact, employers must take employees as they are—even if they’re more vulnerable to injury.
At Employees First Labor Law (EFLL), we help California workers win the benefits they deserve, even when employers and insurance companies try to blame everything on a prior condition.
🔍 1. Are Pre-Existing Conditions Covered by Workers’ Comp?
Yes. If your work aggravated, accelerated, or lit up a pre-existing condition, you may still be eligible for workers’ comp benefits under California law.
📖 Labor Code § 4663: An injured worker is entitled to compensation for the percentage of permanent disability directly caused by the industrial injury, regardless of pre-existing conditions.
This includes:
- Worsening of a chronic back, neck, or knee condition
- Flare-ups of arthritis due to repetitive motion
- Mental health conditions aggravated by job stress
- Re-injury of an old surgical site
⚠️ Important: The key question is not whether you had a prior condition, but whether your job made it worse.
🧠 2. Common Pre-Existing Conditions in Workers’ Comp Claims
| Condition | Work-Related Aggravation |
|---|---|
| Degenerative disc disease | Lifting or standing worsens back pain |
| Carpal tunnel syndrome | Repetitive typing or machine work triggers flare-up |
| Arthritis | Labor-intensive work leads to joint inflammation |
| Mental health issues | High-stress work exacerbates anxiety or PTSD |
| Old fractures/surgeries | Re-injury or overuse of previously healed area |
🔎 Example: A warehouse worker with prior knee surgery develops swelling and pain after climbing stairs and squatting on the job. The employer must address the new cumulative trauma, even if the knee was already compromised.
⚖️ 3. Apportionment: How Disability Is Divided
Apportionment is how a doctor separates your permanent disability between:
- Work-related injury, and
- Non-industrial causes (e.g., pre-existing conditions)
Your doctor must explain this in a medical-legal report (QME or AME) under Labor Code § 4663 and 4664. But many insurers use apportionment to unfairly reduce what they owe.
🧠 Pro Tip: EFLL challenges improper apportionment by demanding detailed rationale from doctors and bringing in second opinions when needed.
❌ 4. Common Employer/Insurance Company Tactics
| Tactic | EFLL Response |
|---|---|
| “It’s not our fault—they were already injured” | We show the new cumulative trauma or workplace acceleration of the condition |
| “It’s just a flare-up” | Even temporary aggravations qualify for medical treatment and temporary disability |
| “Doctor says it’s 100% pre-existing” | We challenge the apportionment and request a Qualified Medical Evaluation (QME) |
| “Claim denied due to prior history” | Prior conditions don’t disqualify you under California law—we’ll appeal immediately |
💵 5. What Benefits Can I Receive If I Have a Pre-Existing Condition?
Even if you had an old injury, you may still qualify for:
- Medical care to treat the aggravated condition
- Temporary disability (TD) while you’re unable to work
- Permanent disability (PD) for the worsened state
- Supplemental Job Displacement Benefits if you can’t return to your prior job
- Settlement compensation (Stipulated Award or C&R)
📚 See also: C&R vs. Stipulated Award Settlements
🛠️ 6. What If My Doctor Blames My Old Injury?
Don’t give up. EFLL will:
- Review your prior medical records and new diagnostics
- Challenge improper apportionment with a QME/AME
- Obtain testimony from treating doctors
- Show how your job significantly worsened your condition
Even if the old injury caused 50% of the issue, you’re still entitled to workers’ comp benefits for the other 50%.
🧾 7. What If My Employer Knew About My Condition?
Even if your employer knew about your pre-existing condition, they must still cover any new work-related aggravation. California follows the “eggshell employee” rule—meaning employers take you as they find you.
⚖️ Case law support:
Escobedo v. Marshalls (2005) 70 Cal.Comp.Cases 604 — Workers are entitled to benefits for work-related aggravation of pre-existing conditions, but apportionment must be medically justified.
📞 8. Get the Benefits You Deserve—Regardless of Your Medical History
Don’t let the insurance company dismiss your claim because of a prior condition. You’re entitled to fair treatment, and EFLL knows how to fight back when they try to minimize your injuries.
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