Undue influence in contract law
If undue influence is proved in a contract (at least in Australia), the contract is voidable by the innocent party, and the remedy is rescission. There are two categories to consider:
* Presumed undue influence
* Actual undue influence
Presumed undue influence
First subgroup
In the first subgroup, the relationship falls in a class of relationships that as a matter of law will raise a presumption of undue influence. Such classes include:
* Parent/child
* Guardian/ward
* Priest/member of parish
* Solicitor/client
* Doctor/patient
In such cases, the onus of proof lies on a doctor, say, to disprove undue influence on a patient.
Second subgroup
The second subgroup covers relationships that do not fall into the first subgroup, but on the facts of case, there was an antecedent relationship between the parties that led to undue influence. The test is one of whether there was a relationship of such trust and confidence that it should give rise to such a presumption (see Johnson v. Buttress (1936) 56 CLR 113).
Actual undue influence
An innocent party may also seek to have a contract set aside for actual undue influence, where there is no presumption of undue influence, but there is evidence that the power was unbalanced at the time of the signing of the contract.