(B) THE ELEMENTS OF DURESS
When determining whether the claimant can rely on duress as a ground of restitution, two separate questions always need to be examined.
(i) Illegitimate Threats and Pressure
Duress involves either the defendant threatening to do something unless the claimant transfers a benefit to him or her, or the actual exertion of pressure until the benefit is transferred. A useful definition of ‘threats’ has been suggested by Smith: ‘A threat is a proposal to bring about an unwelcome event unless the recipient of the proposal does something (e.g. enter a contract), where the proposal is made because the event is unwelcome and in order to induce the recipient to do the thing requested.’
It is possible to distinguish a threat from a warning, on the basis that the person making the warning does not have control over whether the unwelcome consequence will occur. Similarly, a threat is different from a request, which involves the defendant asking for something. Although a theoretical distinction can readily be drawn between threats, warnings, and requests, in practice it is much more difficult to make such distinctions. Threats are normally made expressly, but they can also be implicit. For example, if the defendant goes to the claimant’s house accompanied by three thugs and asks for money, the implicit threat is that, unless the claimant pays the defendant, the thugs will beat him up.
Where the defendant has threatened to do something to the claimant unless the claimant transfers a benefit it is clear that duress will only be established if the threat was illegitimate, but this provides little assistance since it is still necessary to determine what makes a threat illegitimate. In assessing this, both the nature of the threat and the nature of what the defendant demands need to be considered.
Duress can, generally, only be established where the defendant’s threat is unlawful. The threat can be unlawful for two reasons. First, and most usually, because what the defendant threatens to do is unlawful. Consequently, threats to commit crimes or torts, such as threats to injure the person or to interfere with property, are unlawful, as are threats to breach a contract. Secondly, the defendant may actually be threatening to do something which is lawful, but in circumstances where the making of the threat is unlawful. The best example of this is where the threat constitutes the crime of blackmail, which is defined as the making of an unwarranted demand with menaces. This offence can be committed even where what the defendant is threatening to do is lawful, such as threatening to reveal some compromising conduct, but the defendant demands money as payment for not fulfilling the threat.
Exceptionally, however, the making of a lawful threat will be sufficient to establish duress, but only where the threat can be considered to be illegitimate because it is unreasonable. This extended interpretation of a relevant threat was considered by the Privy Council in Rv Attorney-General for England and Wales. In this case the claimant, a member of the Special Air Service (the SAS), which is a celebrated regiment in the British army, was required to sign a confidentiality agreement to stop him from writing about his exploits as a member of the SAS. Failure to sign the agreement would have meant that he would have to leave the SAS and join another regiment. The claimant signed the agreement and then sought to have it set aside by virtue of duress. This argument failed because it was held that the threat to transfer him to another regiment was both lawful and legitimate, since the Ministry of Defence was entitled to conclude that anybody who failed to sign the agreement was unsuitable to remain a member of the SAS. But it was accepted that, had the threat been unreasonable, it would have been sufficient to establish duress even though it was lawful. Subsequently, the courts have explicitly recognized that a lawful threat can be illegitimate, particularly where it was coupled with prior unlawful
It is not sufficient for the claimant to establish that the threat is either unlawful or illegitimate, since it must also be shown that what the defendant demands from the claimant is not lawfully due to the defendant. For example, ifthe claimant owes the defendant ?1,000, and the defendant threatens to seize the claimant’s property unless the debt is repaid, although the threat is unlawful the demand is not, because the debt is owed to the defendant and payment of the money will discharge the debt, so that there is a legally effective basis for the payment. Duress can only be established where what the defendant seeks from the claimant is something to which the defendant is not entitled. Where some money is lawfully due to the defendant and an additional amount is paid because of duress, the claimant will only be able to recover the excess amount.
Where the defendant actually exerts pressure to obtain a benefit from the defendant, rather than simply threatening to exert pressure, the pressure exerted must be illegitimate. Whether it is illegitimate is determined in a similar way to illegitimate threats. First, the pressure must involve the commission of an unlawful act, such as a crime, tort, or breach of contract. Secondly, it must be shown that what the defendant seeks from the exertion of the pressure is not lawfully due to him or her. So, for example, if the defendant falsely imprisons the claimant until she pays ?1,000, which is not otherwise due to the defendant, the claimant will be able to establish that the defendant exerted illegitimate pressure.
-  As was recognized by the Privy Council in Barton v Armstrong  AC 104, 121 (Lords Wilberforceand Simon). See also The Universe Sentinel  1 AC 366, 400 (Lord Scarman) and The Evia Luck  2AC 152, 165 (Lord Goff).
-  S Smith, ‘Contracting Under Pressure: A Theory of Duress’ (1997) 56 CLJ 343, 346.
-  Ibid.
-  The Alev  1 Lloyd’s Rep 138, 142 (Hobhouse J).
-  Barton v Armstrong  AC 104. See also The Universe Sentinel  1 AC 366, 384 (Lord Diplock);R v Attorney-General of England and Wales  UKPC 22.
-  R v Attorney-General of England and Wales  UKPC 22, .
-  Mutual Finance Ltd v John Wetton and Sons Ltd  2 KB 389, 395 (Porter J).
-  Contrary to s 21 of the Theft Act 1968. See Thorne v Motor Trade Association  AC 797, 806(Lord Atkin).
-   UKPC 22. See also Royal Boskalis Westminster NV v Mountain  QB 674.
-  Rv Attorney-General for England and Wales  UKPC 22, .
-  Borelli v Ting  UKPC 21; Progress Bulk Carriers Ltd v Tube City IMS LCC  EWHC 273(Comm);  1 Lloyd’s Rep 501 (Comm),  (Cooke J). For criticism of this expansion of duress, see p 215,below.
-  See p 144, above. 34 See Astley v Reynolds (1731) 2 Stra 915, 93 ER 939.
-  35 See Twyford v Manchester Corporation  Ch 236 and Crescendo Management Pty Ltd v Westpac