Interventions with External Effects – Tripartite Relationships in the Law of Negotiorum Gestio

PhD Project

If a person (intervenor) intrudes into the sphere of interests of another person (principal) without being authorized to do so (intervention), legal relationships arise between the intervenor and the principal. The situation becomes more complex when the intervention involves third parties – for instance, when the intervenor concludes a contract with a third party. In such a tripartite relationship, further questions arise: does an additional legal relationship arise solely between the intervenor and the third party? Or is the intervenor also permitted to establish legal relationships between the principal and the third party? If the latter is the case, what requirements must the intervention fulfil? These questions have been answered differently by German law, the laws of other jurisdictions, historical legal systems, and initiatives aimed at legal harmonisation. These various answers are first systematised using a historical-comparative methodology. The systematised findings are then evaluated against the interests of the parties involved. Finally, doctrinal analysis is used to examine whether, and how, a solution that appropriately reflects these interests can be integrated into the German legal system in a systematically coherent manner.