(C) RESTITUTIONARY CLAIM FOUNDED ON THE REVERSAL OF THE DEFENDANT’S UNJUST ENRICHMENT
Where the restitutionary claim is founded on the reversal of the defendant’s unjust enrichment even though the defendant has also committed a wrong, then, by virtue of the principle of alternative analysis, any defence which applies to an action founded on the wrong should not be applicable to the claim founded on unjust enrichment. This is because the claimant does not need to establish the wrong in order to show that the defendant has been unjustly enriched. It follows that the claimant could avoid the application of defences which relate to the wrong by founding the claim on unjust enrichment instead. But, before the court allows this to happen, it should carefully consider whether the policy which underlies the defence should be extended to a claim founded on unjust enrichment. This is exactly what the House of Lords did in The Universe Sentinel,[1] where the claimant sought to recover money which had been paid to the defendant trade union as a result of its threats that, unless the money was paid, it would prevent the claimant’s ship from sailing. The restitutionary claim was founded on the reversal of the defendant’s unjust enrichment, the ground of restitution being economic duress. The claimant could also have sued the defendant for the tort of interfering with contract, but it had not done so because there was a statutory immunity in favour of the defendant in respect of torts which were committed in the furtherance of a trade dispute. The question for the House of Lords was whether the policy underlying this statutory provision should be extended to the action founded on unjust enrichment. It was held that the immunity should be extended to the restitutionary claim.[2] This was an appropriate decision because the statutory immunity was not dependent on the nature of the cause of action on which the claim was based, but was concerned with whether the defendant should be held liable for any remedy in respect of conduct which related to a trade dispute.
