Informed consent is the requirement that a doctor or physician explain to a patient the nature of a medical procedure or treatment and all special, material or unusual risks or complications associated with it prior to proceeding with the procedure or treatment. In some instances, a doctor is also required to discuss any alternative treatments reasonably available for the patient. 

In Canada, a claim for lack of informed consent requires proof not only that the patient would not have undergone the procedure or treatment in question if the appropriate information was provided, but also that a reasonable person in the same circumstances as the patient would not have consented to the treatment or procedure had all of the appropriate information been provided.