Undue Influence

Undue influence is an equitable doctrine, developed primarily in English and Commonwealth common law, that allows a court to set aside a contract, gift, or testamentary disposition where one party's free will was overborne by another who held a position of trust, dominance, or ascendancy over them.

Courts typically divide undue influence into two categories:

• Actual undue influence, where the claimant proves affirmative acts of coercion, pressure, or improper persuasion that fell short of duress but compromised independent judgment.
• Presumed undue influence, which arises from the nature of the relationship between the parties. Certain relationships — solicitor and client, doctor and patient, parent and child, trustee and beneficiary, religious adviser and disciple — automatically raise the presumption. Other relationships can give rise to a presumption if the claimant shows a relationship of trust and confidence in fact.

The leading modern English authority is Royal Bank of Scotland plc v Etridge (No 2) [2001] UKHL 44, which restated the doctrine in the context of spouses guaranteeing each other's debts and set out steps lenders must take to avoid being fixed with constructive notice of undue influence. Earlier foundational cases include Allcard v Skinner (1887) and Barclays Bank plc v O'Brien [1993].

In probate law, undue influence is a recognized ground for invalidating a will, though the burden of proof is notoriously high; the influence must amount to coercion, not mere persuasion or affection.

The doctrine also appears in civil law jurisdictions under related concepts such as violence morale or exploitation of a state of necessity, and in international human rights and election law, where "undue influence" on voters is prohibited — for example, under section 115 of the UK Representation of the People Act 1983. In contract law more broadly, undue influence sits alongside duress, misrepresentation, and unconscionability as a vitiating factor.