Injury compensation lawyer Clyde: impairment explained

Two measurements do most of the work when an injury is serious. One is the threshold line, which separates soft tissue and some psychological injuries from everything else. The other is whole person impairment, a percentage that describes lasting impairment. Between them, they affect how long statutory benefits can run and what a damages claim, if you have one, can include.

People are often surprised by how technical WPI is. It is assessed under guidelines that rate specific impairments, such as lost movement in a joint, and express the result as a whole-body percentage. More than 10% is the key line in CTP claims, because damages for non-economic loss, meaning pain and suffering, are only available above it. Loss of earnings doesn't need that level.

It's easy to overstate the 10% line. You don't need more than 10% WPI to claim damages for past and future loss of earnings; you need an injury that's more than threshold, another driver at fault, and not to have been mostly at fault yourself. The 10% line decides pain and suffering, and it also affects some timing rules for a damages claim.

Serious physical injuries often bring a psychological toll: sleeplessness, anxiety, depression or trauma symptoms. These can be part of your claim in their own right. Tell your doctor how you're coping, and ask about psychology if it would help. Whether a psychological injury is threshold or more is a medical and legal question, and the insurer's decision on it can be reviewed.

The threshold line is a medical line drawn by legal rules. Your doctor diagnoses the injury; the scheme's definition decides which side it falls on. Sprains, strains and whiplash without nerve findings usually sit on the threshold side. Confirmed nerve damage, a tear, a fracture or a brain injury generally takes an injury beyond it. The insurer makes the call, and you can challenge it.

The line also decides whether common law damages are open. With only a threshold injury, they generally aren't. With a more serious injury, you may be able to claim damages if another driver was at fault and you weren't mostly at fault. That is why a threshold decision is often the most important decision the insurer makes about a serious injury.

Earning capacity compares what you could have earned without the injury with what you can realistically earn now. For a tradesperson with a damaged shoulder, or an office worker with a brain injury, that gap can be large and long-lasting. Record every change to your working life: hours, duties, roles you can no longer do. Those facts sit alongside the medical evidence.

There's usually no single moment when WPI is measured. Opinions may come from treating doctors, from doctors the insurer arranges, and, where the two sides disagree, from a medical assessment through the Personal Injury Commission. Timing matters, because injuries can improve or worsen for months. A lawyer can advise whether an assessment is premature before you rely on it.

• Whether every injured body part is included
• Scans or tests your doctors have ordered
• Whether you disagree with the result, and the deadline to say so

The most persuasive serious injury claims usually have consistent evidence: the same injuries described the same way, from the hospital to the GP to specialists, with no unexplained gaps in treatment. That consistency comes from telling each doctor the full story and following treatment plans. If a report leaves something out, ask the doctor about it rather than letting it pass.

• Hospital admission and discharge records
• Operation and specialist reports
• Records of how the injury affects your work
• Any impairment assessment, and your response to it