Buyer’s title insurance is optional in Canada. Paying the premium is entirely at your discretion. It’s a commonplace to buy title insurance when you first close the deal on your home. However, because the policy deals with past events before you assumed ownership, you can still get title insurance even if you are already a property owner.
Title insurance will cover the cost (up to the maximum coverage) arising from legal proceedings concerning ownership of the property. It deals explicitly with claims brought against the policy owner. It will not, however, cover the cost of any lawsuits initiated by the policyholder.