Equity has traditionally recognised a category of estoppel known as proprietary estoppel. Proprietary estoppel is a doctrine that applies where a person induces another to adopt an assumption or expectation that the other has or will obtain an interest in the first person’s property, and on the basis of this assumption the other person alters their position or acts to their detriment.
The onus of proof in establishing the estoppel has always been on the party who relied on the assumption or expectation.
The recent case of Sidhu and Van Dyke  HCA 19 looked at this position and the High Court has rejected the notion that the onus of proof in relation to detrimental reliance can shift to the party said to be estopped.
When acting for a tenant, it is important to ensure the tenant understands its obligations as to how the premises are to be delivered to the landlord at the end of the lease term. This is known as the “make good” obligations of the tenant and will be governed by the provisions in the lease.
Landlords need to be extremely careful about what representations they make when negotiating leases as section 243 permits the court to make an order declaring the whole or any part of a contract void or to vary a contract.
In the recent case of Willmott Growers Group Inc v Willmott Forests Limited, the High Court upheld the decision of the Victorian Court of Appeal which held that liquidators of a landlord company can use the disclaimer power in the Corporations Act 2001 to extinguish leases granted by that company. So what does this mean for tenants and does this have any effect on mortgagees of a landlord company?