INTRODUCTION

The third party is omnipresent, yet hard to define in law. There is one foundational principle which has set the stage throughout legal history: alteri stipulari nemo potest – no-one may stipulate for another. Third persons find themselves, thereby, principally placed outside another's obligation – this vinculum iuris (chain of law) which binds debtor to creditor. Justinian's metaphor characterises the obligation between the parties, and also signifies its exclusionary force towards third parties. It is not just a principle from civil law, but is similarly strongly present in common law traditions of privity of contract:

Yet contracts and obligations not only appear in juridicial vitro – in the books – but also in vivo – in practice. Hence, third parties have quite commonly appeared in the actual world of transactional practice throughout history.

The third party found its bond as a debtor or creditor only with difficulty, established in the variety of legal formants over time, whereby schools of legal thought, sources of law, means of reasoning, as well as substantive concepts provided the building blocks making or breaking the third parties’ position. The factual variety in social reality adds to the picture.