A personal guarantee represents one of the most serious financial commitments a business owner can make, yet when a creditor comes calling to enforce that guarantee, the guarantor is not necessarily without recourse. Canadian law recognizes a range of defences that may allow a guarantor to resist payment, reduce the amount claimed, or escape liability altogether. Understanding these defences is essential for any business owner, sole proprietor, or non-profit operator who has signed a guarantee, because the strength of a potential defence often depends on actions taken or omitted long before any dispute arises.
The foundation of guarantee defences lies in the nature of the guarantee itself as a contract. Like any contract under Canadian law, a guarantee must satisfy basic requirements to be enforceable: there must be an offer and acceptance, consideration, certainty of terms, and the parties must have the legal capacity to contract. Beyond these fundamental requirements, guarantees are subject to additional rules that reflect their unique character as secondary obligations dependent on a primary debt. In the common law provinces, which include British Columbia, Alberta, Saskatchewan, Ontario, and the remaining provinces outside Quebec, the law of guarantees developed through centuries of judicial interpretation emphasizing protection for guarantors who often receive no direct benefit from the transaction they are guaranteeing. Quebec's Civil Code of Quebec establishes a similar but distinct framework rooted in the civil law tradition, with specific provisions governing suretyship found in articles 2333 through 2366 as of the date of authorship. Despite the different legal traditions, both systems recognize that guarantors occupy a vulnerable position and provide defences accordingly.