Does Signing a Consent Form Mean You Can’t Sue?

Many patients assume that once they sign a consent form before a medical procedure, they have given up their right to sue if something goes wrong. In Ontario, this is a common misconception.

Signing a consent form does not automatically prevent a lawsuit. A consent form is one piece of evidence, but it does not override a healthcare provider’s legal obligations or eliminate a patient’s rights.

What a Consent Form Does…and Does Not Do

A consent form is intended to document that a patient agreed to undergo a proposed treatment or procedure. It can help demonstrate that consent was discussed, but it is not determinative of whether valid consent was actually obtained.

A signed form does not:

• Act as a waiver of liability;
• Shield a healthcare provider from negligence claims; or
• Prove that a patient truly understood the risks involved.

Ontario courts have repeatedly emphasized that consent is a process, not a piece of paper.

Informed Consent Under Ontario Law

In Ontario, consent to treatment is governed by the Health Care Consent Act, 1996. For consent to be legally valid, it must be:

• Given by a capable patient (or a legally authorized substitute decision-maker);
• Voluntary, without pressure or coercion; and
• Informed.

“Informed consent” requires that the patient be given information a reasonable person would want to know before deciding whether to proceed. This includes:

• The nature of the proposed treatment;
• Its expected benefits;
• Material risks and potential complications, even if uncommon but serious;
• Reasonable alternative treatments; and
• The likely consequences of declining treatment.

A signed consent form cannot replace this discussion. If the discussion was inadequate or misleading, or if material information was not disclosed to the patient, the consent may be legally invalid.

Recent Guidance from the Ontario Court of Appeal

In the 2024 appeal of Denman v. Radovanovic, the Ontario Court of Appeal reaffirmed and clarified the law of informed consent. The Court emphasized that:

• The duty to obtain informed consent is patient-focused, not physician-focused;
• The main inquiry is whether the patient and a reasonable person in the patient’s circumstances would have elected to proceed with the treatment had adequate disclosure been made;
• In multi-step or ongoing treatment plans, the duty to obtain informed consent may arise at more than one stage, involve disclosure of cumulative risks, and may rest with more than one physician involved in the patient’s care, including those who are not directly involved in administering the treatment or procedure.

Importantly, the Court confirmed that the presence of consent forms does not resolve the issue. The focus remains on the substance of the disclosure, not the paperwork.

You Can Still Sue After Signing a Consent Form

A patient may still have a valid legal claim even after signing a consent form, including where:

• Material risks were not disclosed;
• Risks were minimized or not explained in understandable terms;
• The patient was not told about reasonable alternatives;
• The procedure performed differed from what was discussed; or
• The treatment was carried out negligently.

Ontario courts assess what the patient was actually told and understood, not merely whether a form exists in the medical record.

Consent is Not a Waiver of Negligence

Consent allows a healthcare provider to perform a procedure. It does not excuse negligent care.

A patient does not consent to:

• Diagnostic errors;
• Surgical mistakes;
• Improper technique;
• Failure to monitor or respond to complications; or
• Care that falls below accepted standards of practice.

Even where a known risk materializes, liability may still arise if the harm was caused by negligent care rather than the inherent risk itself.

Why the Details Matter

In informed consent cases, Ontario courts apply a patient-centered analysis. The key question is whether the patient and a reasonable person in the patient’s position would have proceeded with the treatment had adequate disclosure been made.

Informed consent disputes are highly fact-specific. Courts will often assess:

• What the patient was told, and when;
• Whether the information was tailored to the patient’s circumstances;
• Whether the risk that materialized was one a reasonable patient would have considered significant; and 
• Whether the patient would have proceeded had proper disclosure been made.

Medical records, testimony, and expert evidence all play a role. A signed consent form is relevant, but it is rarely decisive on its own.

Key Takeaways

In Ontario, signing a consent form does not mean you cannot sue. Consent forms do not waive legal rights, excuse negligence, or replace a healthcare provider’s duty to obtain informed consent and provide competent care.

If harm occurs despite a signed consent form, the issue is not whether consent was signed but instead whether it was properly obtained and the patient’s choices properly respected.