“If I’d Known, I Wouldn’t Have Agreed”: Informed Consent and Undisclosed Risks
Summary
Before treatment, you should be told about the material risks: those a reasonable person would want to know, and those that matter to you. When a risk you weren’t told about happens, you may wonder whether you would have chosen differently. This guide explains what informed consent means in Australia, how the law decides whether a failure to warn matters, and what your records can show.
Quick answer · updated November 2026
Doctors must warn you of material risks (Rogers v Whitaker). If an undisclosed risk happens, the law asks whether you would have declined or chosen differently if warned. Wallace v Kam says you can recover only for an injury from a risk you would not have accepted. In NSW, what you say now about what you would have done isn’t admissible on that question, so your circumstances and records matter. It is always worth having consent looked at.
Informed consent at a glance
- 1The dutyWarn of material risks.
- 2The conversationOptions, risks and your priorities.
- 3The formA record, not a substitute.
- 4If a risk happensWould you have chosen differently?
- 5EvidenceRecords and your circumstances.
At any stage: consent is a conversation, not a signature. See what the form does and doesn’t prove.
I’m a piano teacher. Before my hand surgery, I asked the surgeon whether it could affect my playing. He said it was a straightforward procedure.
Afterwards two of my fingers were numb and clumsy. The surgeon said nerve damage was a known risk.
I told him I would never have gone ahead if I’d known. I would have kept managing with splints.
He said it was on the consent form.
A composite story, drawn from the experiences of many families I have worked with, combined and changed so that no one can be identified. It does not describe any individual client.
If a risk you weren’t told about has happened to you, I want you to know that your feelings are valid and your questions are important. Consent is about your right to decide what happens to your body.
This guide covers what doctors must tell you, how the law treats failure to warn, what your records show, and how to think about your own situation.
Why I can write this
I have been a medical negligence lawyer since 2014 and have worked on many hundreds of claims, including many involving consent. My doctorate looked at patterns of failure in medical negligence. I am not medically qualified. The clinical facts in this article are checked against named sources, listed in the references, and I explain how I work in our editorial standards.
Start with your question
- What is a material risk?
- What should I have been told?
- Is signing a consent form enough?
- Do I have to prove I would have said no?
- What did Wallace v Kam decide?
- What evidence matters?
- Can I claim for failure to warn?
Material risks
In Rogers v Whitaker, the High Court held that doctors must warn of material risks: those a reasonable person in the patient’s position would be likely to attach significance to, and those the doctor knows or should know the particular patient would.1 That second part matters when you have told the doctor what is important to you.
Definition
Material risk means a risk a reasonable person, or you in particular, would want to know about.
In plain terms: a risk that could change your decision.
The conversation
Informed consent involves accurate information about options, benefits and material risks, given in a way you understand, with time to decide.2 Our guides to consent before spinal surgery and questions before revision surgery give examples.
Questions to ask
- What are the risks that matter most for someone like me?
- What are the alternatives, including doing nothing?
- Is there anything about my job or life that changes the risks?
- Can I have this in writing?
The form
A signed form is evidence a conversation happened, but it doesn’t prove what was said or understood. A long list of small-print risks may not show that the risk that mattered to you was discussed.
Would you have chosen differently?
Showing the risk wasn’t disclosed is only part of it. The law also asks whether, if warned, you would not have had the treatment, or would have had it at a different time, place or with a different practitioner.
Wallace v Kam
In Wallace v Kam, the High Court held that a doctor who negligently failed to warn of a risk was not liable for an injury from that risk because the patient would have accepted it if warned. The duty to warn protects patients from injuries they would find unacceptable to risk.3
Evidence
In NSW, what you would have done if warned is decided subjectively in light of all the circumstances, and your own statement after the harm about what you would have done is inadmissible, except to the extent it is against your interest (Civil Liability Act 2002 (NSW) s 5D(3)). That is why your circumstances matter: your job, your priorities, what you asked, and what alternatives existed. Notes of your questions and the letters to your GP can be powerful.
If something has gone wrong now
See your doctor
- A new complication
- Numbness or weakness
- A result you weren’t expecting
In plain terms: get it assessed and recorded.
Urgent
- Severe pain
- Signs of infection
- Sudden loss of function
In plain terms: seek care today.
When I got my records, the surgeon’s letter to my GP said “risks discussed”. The form listed “nerve damage” among twelve items.
But my GP’s referral letter said I was a professional pianist concerned about fine motor function. The surgeon had that letter.
A hand therapist says my fingers may improve, but probably not to concert standard.
My partner read the referral letter and said, “He knew exactly what mattered to you.” That’s the part I keep coming back to.
A composite story, drawn from the experiences of many families I have worked with, combined and changed so that no one can be identified. It does not describe any individual client.
What to look for in the records
Your records are often where the story becomes clear. You have a right to access your own health information. In NSW the Health Records and Information Privacy Act 2002 covers both public and private providers, and the Information and Privacy Commission explains how to ask.4 Our step-by-step guide to getting your medical records in Australia walks you through it.
| Record | Why it matters |
|---|---|
| Referral letters | What your GP told the specialist about you. |
| Consultation notes | What you asked and what was said. |
| Consent form | What risks were listed and when you signed. |
| Information leaflets | Written information you were given. |
| Letters to your GP | The specialist’s account of the discussion. |
| Your own notes | Questions you wrote down at the time. |
| Your own diary, photos and messages | Notes made at the time are evidence too. Keep them. |
How the law looks at it
A complication after treatment is not automatically a failure to warn, and a failure to warn doesn’t automatically lead to compensation. But consent cases are always worth looking into, because the details of what you were told and what mattered to you can make all the difference.
A claim usually turns on three questions: whether the care fell below what peers would widely accept as competent practice (section 5O of the Civil Liability Act 2002 (NSW))5, whether that shortfall probably caused harm you wouldn't otherwise have had (Tabet v Gett)6, and, where it matters, whether you were told the material risks first (Rogers v Whitaker)12. Our guide to how a medical negligence claim works explains each one in plain terms.
In a consent case, the questions might be: was the risk material for a reasonable person, or for you in particular? Did you raise concerns that should have prompted a specific warning? Were alternatives explained? Was the conversation adequate, rather than just a form?
In plain terms, the question is whether, properly warned, you would probably have declined the treatment or chosen a different path, so that the injury would not have happened.
This whole article is about consent. The key cases are Rogers v Whitaker on the duty, and Wallace v Kam on causation.
Who can claim, and when
The person who had the treatment can claim. If they have died, their family may have a claim. In NSW, time usually runs from when you knew, or ought to have known, enough to claim, not from the treatment itself, and courts can sometimes extend it, so an old injury may still count. See time limits in NSW or other states, and ask early.
More: complaint or claim? · how a claim is paid for · what a claim can cover
In my practice
In consent files, the referral letter is often the most important document. It shows what the doctor knew about the patient’s job, hobbies and priorities before the consultation. When a patient said “I’m a pianist” or “I can’t afford time off work”, the duty to warn about risks to those things is much clearer.
Both things can be true
Your surgeon may have operated skilfully and still not told you what you needed to know. Both can be true.
The bigger picture
Informed consent is a core part of the national safety standards.2 You can check a practitioner on the Ahpra public register,7 and complaints about care in NSW can go to the Health Care Complaints Commission.8 Our guide to getting your medical records explains how to ask for your file.
Support
You don't have to work through this alone. These services can help:
- Lifeline, 24-hour crisis support: 13 11 14 (listed on healthdirect's helplines page)9
- Beyond Blue, anxiety and depression support: 1300 22 4636
- Medicare Mental Health, help finding mental health support: 1800 595 212
- healthdirect, 24-hour nurse advice: 1800 022 222
- Health Care Complaints Commission (NSW): 1800 043 159
A piano teacher who asked about her hands now knows the surgeon had her letter. You deserve to be heard too.
With care,
Rosemary
Frequently asked questions
What is a material risk?
A risk a reasonable person, or you in particular, would want to know about.
Is a signed consent form enough?
No. It records a conversation but doesn’t replace one.
Do I have to prove I would have refused?
The law asks whether, if warned, you probably would have chosen differently.
What was Wallace v Kam about?
Causation: no recovery for an injury from a risk you would have accepted.
Can I just say I would have refused?
In NSW, that statement alone isn’t admissible; your circumstances are the evidence.
Can I claim for failure to warn?
You may well have a claim if a material risk wasn’t disclosed and you would have chosen differently.
Weren’t told about a risk?
When you're ready, and not before, I can look at what happened and help you understand your options.
Consent guides
- “If I’d known, I wouldn’t have agreed”: Informed consent and undisclosed risks (you are here)
- Bulk billing and consent
- Consent before spinal surgery
- Open disclosure
Part of our guide to surgical errors and hospital negligence. Not sure where you stand? Try the free claim checker.
References
- Rogers v Whitaker [1992] HCA 58; (1992) 175 CLR 479.
- Australian Commission on Safety and Quality in Health Care. Informed consent.
- High Court of Australia. Judgment summary: Wallace v Kam [2013] HCA 19.
- Information and Privacy Commission NSW. Fact sheet: Accessing your health information in NSW.
- Civil Liability Act 2002 (NSW) s 5O, Standard of care for professionals.
- Tabet v Gett [2010] HCA 12.
- Australian Health Practitioner Regulation Agency. Register of practitioners.
- Health Care Complaints Commission NSW. Home page.
- healthdirect Australia. Mental health helplines.
Stories in this article are composites, drawn from the experiences of many families I have worked with, combined and changed so that no one can be identified. They do not describe any individual client.
Dr Rosemary Listing, PhD (Law), Medical negligence lawyer since 2014 · Of Counsel, Peter Evans & Associates. Rosemary's doctorate examined patterns of failure in medical negligence, and she teaches health law at the University of Newcastle. She is not medically qualified. About Rosemary.
Last updated: 10 November 2026 · First published: 10 November 2026 · Next review: May 2027
Cite this article: Listing R. “If I’d known, I wouldn’t have agreed”: Informed consent and undisclosed risks. Reframe Legal. Published 10 November 2026. https://reframelegal.com/if-id-known-the-risk-consent/
This article is general information, not legal or medical advice. It does not create a lawyer–client relationship. Speak to your treating clinicians about your health, and get legal advice about your own situation.
If you are in danger or need urgent medical help, call 000. For crisis support, call Lifeline on 13 11 14.
Legal services are provided by Peter Evans & Associates.
