The Substitute Decisions Act, 1992 governs substitute-decision making with respect to property and health. A Power of Attorney is signed during the life of the client and during a period that they are capable. This grants an appointed attorney the power to act on behalf of the grantor in the case of: 1) incapacity; and 2) capacity but grantor is not available to make decisions.
If you do not have a Power of Attorney during incapacity, you do not have control over the person that becomes the attorney. It will also involve a much more difficult and costly process.