Should duress require 'illegitimate' pressure or focus on outcome?
Andrew Burrows has argued that the legitimacy enquiry should be replaced or supplemented by a test asking whether the resultant contract is substantively fair. He reasons that lawful threats can vitiate consent if they procure an unconscionable transaction. This approach aligns with civilian and Restatement models.
Mindy Chen-Wishart (Contract Law, 6th ed, 2018) defends the current framework, arguing that legitimacy is essential to distinguish ordinary commercial negotiation—where parties routinely threaten to walk away—from duress. She contends that focusing on substantive fairness risks unpredictability and judicial paternalism. The law must permit hard bargaining; only illegitimate pressure vitiates consent.
Stephen Smith ('Contracting under Pressure' (1997) 56 CLJ 343) suggests that duress should be understood through the lens of no-retraction: once a threat is made, the victim cannot retract consent. The focus should be on whether the pressure was such that the law ought not to hold the claimant to the contract. This test is broader than illegitimacy and focuses on the quality of practical choice.
Is undue influence a wrong or a lack of consent?
Peter Birks and Yin Chin ('On the Nature of Undue Influence' in Good Faith and Fault in Contract Law, 1995) argue that undue influence is a species of equitable wrong, akin to breach of fiduciary duty. The defendant's conduct—exploiting trust—is the focus, not the claimant's state of mind. This analysis explains why restitution is available even if the claimant appeared to consent voluntarily.
Rick Bigwood (Exploitative Contracts, 2003) contends that undue influence is better seen as vitiation of consent through relational inequality. The doctrine does not require the defendant to act unconscionably (indeed, Class 2 presumed influence does not require proof of improper motive); rather, it recognises that consent given in certain relationships is not sufficiently autonomous.
These rival accounts have practical implications. The 'wrong' analysis suggests that undue influence should be treated like fraud, requiring proof or presumption of misconduct. The 'consent' analysis permits intervention on the basis of structural inequality, even absent fault. Etridge leans toward the latter, allowing the presumption to arise from the relationship and transaction without proof of improper motive.
Manifest disadvantage: necessary or redundant?
P.R. Capper ('Undue Influence and Unconscionability: A Rationalisation' (1998) 114 LQR 479) argues that requiring disadvantage imports an irrelevant element: undue influence is about autonomy, not prudence. He advocates removing the requirement entirely.
David Capper (a different author) in 'The Need for Manifest Disadvantage' [2003] Restitution Law Review 1 defends some threshold of transactional imbalance as necessary to filter out trivial or spurious claims. Without it, any transaction in a relationship of trust could be challenged years later.
Etridge's compromise—'calls for explanation' rather than 'manifest disadvantage'—attempts to balance these concerns. Lord Nicholls emphasised that the transaction need not be improvident, merely one that 'is not readily explicable by the relationship of the parties'. Academic opinion remains divided on whether this is sufficiently robust or excessively vague.
Should wives and cohabitants be treated as a protected class?
Rosemary Auchmuty ('Men Behaving Badly: An Analysis of English Undue Influence Cases' (2002) 11 SLS 257) argues that undue influence law reflects and entrenches gender inequality. By focusing on whether the wife received advice rather than on the husband's conduct, the law places responsibility on women to protect themselves, rather than penalising exploitative men.
Jill Poole and Agnes Keyser ('Justifying Partial Intervention in Contracts: The Role of the Unfair Contract Terms Act 1977 and the Consumer Rights Act 2015' (2005) 68 MLR 209) argue that suretyship should be regulated by statute rather than equitable presumptions. A bright-line rule (e.g. requiring formalities or cooling-off periods) would provide certainty and better protect vulnerable guarantors.
Janet O'Sullivan (in Virgo & Worthington (eds), Commercial Remedies (2017)) defends Etridge as pragmatic: it acknowledges that many guarantees are entered into freely and would be imperilled by blanket rules, while targeting cases with elevated risk through the 'put on inquiry' mechanism.
Should there be a general doctrine of 'inequality of bargaining power'?
Lord Denning in Lloyds Bank Ltd v Bundy [1975] QB 326 proposed a unifying principle of inequality of bargaining power that would subsume duress, undue influence, and unconscionability. The House of Lords decisively rejected this in National Westminster Bank v Morgan [1985] AC 686, affirming that English law recognises discrete doctrines, each with its own requirements.
Hugh Beale (ed), Chitty on Contracts, 34th ed (2021) defends this pluralism: different vitiating factors have different policies and histories, and a unified doctrine risks conceptual confusion and unpredictable outcomes. Others, including Jack Beatson (now Lord Beatson), have argued that a principled synthesis is possible and would enhance coherence.