Duress is a tort involving unlawful pressure exerted on a person to make them act against their free will. The pressure may involve threats of violence, unlawful detention, or other forms of coercion that undermine genuine consent. The central concern is that the claimant’s decision is not truly voluntary.
Duress arises where a defendant applies illegitimate pressure that forces the claimant into a transaction or act they would not otherwise have agreed to. In Barton v Armstrong (1976), threats of violence were held sufficient to vitiate consent even though the claimant had other commercial reasons for agreeing. The courts focus on whether the threat was a significant factor in the decision-making process rather than the only cause. Ordinary commercial pressure, such as hard bargaining or refusing to contract, is generally lawful. However, once the pressure involves unlawful threats or coercion, liability may follow, and the agreement or resulting loss can be challenged. This distinction ensures that only genuinely oppressive conduct is captured by the doctrine.
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