Serious injury? Injury compensation lawyer, Shortland

An injury can be serious in human terms and still sit on the threshold side of the line, and the reverse can happen too. That can feel unfair. It helps to know the scheme's tests are about the type of injury and its lasting effects, not how much you've suffered. Knowing which test applies lets you and your doctors focus on the evidence that matters.

Whole person impairment, or WPI, is a percentage that describes how much a lasting injury affects the body as a whole. It isn't a measure of pain, and it isn't a measure of what you've lost. It's a medical assessment made under set guidelines once an injury has stabilised. In a CTP claim, WPI matters mainly for damages: non-economic loss is only available where WPI is more than 10%.

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.

A serious injury can change more than the next few months of work. It can limit the kind of work you can do for years, or permanently. In a damages claim, that is called loss of future earning capacity, and it can be a significant part of a serious injury claim. It generally needs evidence from your doctors, your work history and sometimes vocational experts.

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.

Getting the classification right early helps. If you have symptoms that could point to nerve involvement or a tear, such as numbness, weakness, locking or a joint giving way, describe them to your doctor. Whether tests are needed is a medical decision. If a diagnosis changes, make sure the insurer has the new evidence, because the classification may need to change with it.

In a serious injury claim, impairment often comes into focus well after the crash, once treatment has run its course. The Personal Injury Commission handles medical assessment where the insurer and the injured person disagree. If you think an assessment is wrong, the steps to challenge it are set out separately, and the deadlines are short, so act promptly.

• How complete and current your medical records are
• Changes in your condition since the last report
• Whether you disagree with the result, and the deadline to say so

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.

Serious injury claims rest on medical evidence gathered over time: hospital records, imaging, operation reports, specialist opinions, and treating doctors' notes that track your progress. Your own records add the human detail. Start collecting early, keep everything in date order, and make sure each doctor knows about all your injuries, not just the one they're treating.

• 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