Unjust enrichment and civil delictual liability are but the two sides of the same coin, having the same scope without overlapping, juridically speaking. This is obvious when enrichment arises from an illegal interference with another?s property. The French and the Greek legal order seem to be two legal systems maintaining until today the Einheitslehre of unjust enrichment claims. Both orders do not take into account a categorization and a systematization of claims in accordance with the requirements giving rise to an unjust profit. Regardless of the special provisions of each legal system, crucial questions arise in the same way: Would it be possible to consider, under the same perspective, enrichment by undue payment and enrichment due to the forces of nature (e.g. confusio or commixtio)? Is it possible to find a common denominator, as regards the causa, between enrichment with performance and enrichment without performance? How to compare enrichment produced by a person?s interference with another?s property with enrichment born by an undue payment? Is it not rather reasonable to proceed with the theory of separation of claims (Trennungslehre) proposed by German legal scholarship, after Wilburg?s and Von Caemmerer?s legal model of distinction between enrichment based on performance and enrichment not based on performance?
European Review of Private Law