The Health Care Consent Act (HCCA) applies to all aspects of health care in Ontario and provides rules for obtaining informed, voluntary consent from a substitute decision maker. Section 4 of the HCCA outlines the guidelines for consent and capacity (one shall not administer treatment without a patient's consent - otherwise it is battery or assault). The HCCA is what allows you to determine whether treatment can be imposed on an individual if you do not think they are capable. Only a finding of incapacity under the HCCA allows you to treat the patient against their wishes (i.e. - involuntary treatment). Remember, capacity is treatment-specific.
In Ontario, if a patient is found incapable, you must find a Substitute Decision Maker (SDM) to give consent on the patient's behalf. The hierarchy of SDMs is dictated by the Healthcare Consent Act (HCCA). Here are some points to consider when an SDM is involved: