Can a Landlord Sue a Tenant For Causing Injury?
As Per the Occupier's Liability Act and Case Law, Co-Occupiers of Premises, Such As a Landlord and Tenant That Share Common Areas Upon the Premises, Owe a Duty of Care to Each Other to Ensure That the Premises Is Kept Reasonably Safe.
A Brief Outline As a Helpful Guide on How to Determine and Understand Co-Occupier Liability Risks Involving the Occupier's Liability Act:
In Ontario, the Occupier's Liability Act, R.S.O. 1990, c. O.2 prescribes the duty of care owed by an occupier to those who may be upon premises occupied by the occupier. The prescribed duties, with some exceptions, include concerns relating to legal liability for personal injuries or property damage that may arise due to the activities conducted upon the premises or that may arise due to the condition of the premises. The Occupier's Liability Act includes legal principles that prescribe concerns relating to how the law should be applied for issues such as when injuries occur to a person who slips or falls due to slippery snow and ice conditions, among other things. Specifically, the Occupier's Liability Act states:
1 In this Act,
(a) a person who is in physical possession of premises, or
(b) a person who has responsibility for and control over the condition of premises or the activities there carried on, or control over persons allowed to enter the premises,
despite the fact that there is more than one occupier of the same premises;
3 (1) An occupier of premises owes a duty to take such care as in all the circumstances of the case is reasonable to see that persons entering on the premises, and the property brought on the premises by those persons are reasonably safe while on the premises.
As is stated per section 1, an occupier is defined broadly and can include owners, tenants, contractors, among many others, who are in care and control of premises. Furthermore, per section 3, each occupier is prescribed a broad duty of care which is to act reasonably to ensure that other persons, and property of other persons, is reasonably safe while upon the premises. With some exceptions, such as a limited duty owed to trespassers, such as criminals entering onto the premises for unlawful purposes, the duties owed to other persons remains quite broad.
Does a Tenant Owe a Duty of Care to a Landlord?
Yes. The Occupier's Liability Act Prescribes a Duty of Care Upon Co-Occupiers of Premises Concurrent With the Duty of Care Owed to Third Party Strangers to the Premises.
A question of concern that sometimes arises in law is whether an occupier owes a duty of care to another occupier of the same premises. An example could include whether a contractor, being in care and control of premises when hired to perform snow clearing within the parking lot, is owed a duty of care by the janitorial staff whose job it is to shovel the sidewalk that leads to the parking lot. If during the course of the winter period, snow plowed from the parking lot by the contractor was located on, or near, the sidewalk, and then that contractor subsequently (assumedly after a reasonable time) slips on ice accumulating upon the sidewalk as a result of the melting of snow plowed earlier by the contractor, and the ice on the sidewalk is due to the failure of the janitorial staff to tend to the ice, can the janitorial staff be found as owing a duty of care to the contractor? Another interesting example could be whether a landlord and tenant owe duties to each other. In this scenario, imagine a residential dwelling occupied in part by a landlord and in part by a tenant; such as where the landlord is living within a unit upstairs and the tenant within a unit downstairs and both are sharing amentities such as the backyard patio, among some other 'common' areas. In this scenario, did the landlord that leaves an obstacle upon the patio owe a duty of care to the tenant despite that the landlord and the tenant are co-occupiers of the patio? How about the scenario where a husband of wife jointly own a home and the husband negligently leaves a waterspill on a floor leading to a slip and fall with injuries to the wife?
Recently, the Court of Appeal confirmed that co-occupiers may, and often do, owe a duty of care to each other. Such was stated within the case of Nolet v. Fischer, 2020 ONCA 155 where it was expressly said:
 To conclude, there is no language or provision of the Act that one occupier does not owe the duty of care to another occupier, or that provides that when an occupier enters on the premises they are not a person “entering on premises” for the purpose of the Act. Nor is there any basis to read any such legal restriction into the Act. While persons may enter onto premises for many different reasons and may leave quickly or stay indefinitely, the Act creates one duty that is owed to all such persons including those who are also other occupiers.
Occupier liability prescribed by the Occupier's Liability Act includes a duty of care owed to other occupiers. Accordingly, in law, although perhaps uncommonly occurring, an occupier such as a contractor hired to maintain premises may owe a duty of care to another contractor hired to maintain that same premise. A landlord and tenant sharing a common area may owe a duty of care to each other to ensure that that common area is kept free of obstacles and thereby reasonably safe from causing injury to the each other. A husband and wife, each jointly owning the same house, may owe a duty of care to maintain the house is such a manner as to avoid causing hazards that could injure the other.