(ii) Implications for the General Community
Even though the claimant who has paid money to a public authority which was not lawfully due to it, appears to have an absolute right to restitution by virtue of national and EU constitutional considerations, this is complicated by a different consideration ofpublic policy, deriving from the fact that such claims are likely to involve large sums of money, whether because one or two claimants seek to recover large sums or because there are numerous claims for relatively minor sums. Where a public authority has received such sums in circumstances where it can be shown to be unjustly enriched, awarding restitutionary remedies may seriously jeopardize the availability of public funds with consequent deleterious effects on the community. It follows, according to this second public policy argument, that restitutionary claims against public authorities should be deterred for the benefit of the public generally.
(iii) Balancing Principle and Pragmatism
Consequently, the question of whether a restitutionary claim can successfully be brought against a public authority involves a clash of principle and pragmatism. For constitutional principle demands that a public authority which has unlawfully received money should return it, but pragmatism suggests caution, to preserve the security of the public authority’s receipts for the greater public good. These arguments are essentially incompatible but, as will be seen, some form of compromise can be reached by accepting the right of the payer to bring a restitutionary claim but ensuring that the public authority has a number of special defences, or differently interpreted general defences, to ensure that there is no unnecessary disruption of public finances which could have profoundly detrimental effects on the effectiveness of the public authority.