(D) THE APPLICATION OF THE DEFENCE
In Lipkin Gorman Lord Goff recognized that it was not appropriate in that case ‘to identify all those actions in restitution to which change of position may be a defence’. Consequently, the application of the defence needs to be considered in respect of each part of the law of restitution.
(i) Claims Founded on the Reversal of the Defendant’s Unjust Enrichment
Clearly the defence is applicable to founded on unjust enrichment. The operation of the defence to particular types of claim may, however, differ. For example, some grounds of restitution depend on proof, either actual or presumed, of the defendant’s unconscionable conduct and this may be sufficient to prevent the defendant from relying on the defence, since this will constitute evidence of bad faith. Further, the defence will not be available in respect of many claims involving restitution from public authorities, particularly where the receipt of taxes was unlawful by EU law or where the claim is grounded on the Woolwich principle.
-  221 See M Chen-Wishart, ‘Unjust Factors and the Restitutionary Response’ (2000) OJLS 557.
-  222 Prudential Assurance CoLtdvHMRC  EWHC 3249 (Ch),  2 CMLR 10,  (Henderson J).
-  See further p 409, above.
-  223 Test Claimants in theFII Group Litigation vHMRC  EWHC 4302 (Ch),  EWHC 4302 (Ch).
-  See p 693, above.