Nieważne zobowiązania ex stipulatione. Znaczenie “Impossibilium nulla obligatio est” Celsusa (D. 50,17,185) w prawie rzymskim

This article concerns the issues of invalid obligations ex stipulatione and the meaning of the Celsus phrase Impossibilium nulla obligatio est (D. 50,17,185) in Roman law. It presents in a polemic way two groups of the opinions, which can be found in the literature. The older theories adapt the civil law achievments to the ground of Roman law, what does not help to understand the concept of initial impossibility in Roman law. This research method is concentrate on the function of impossibility and does not indicate the reason of invalidity of the ex stipulatione obligations. At the same time it does not explain the meaning of the Celsus sentence. In the opposition there are in the newer literature an alternative theories to found, which analyse the invalid obligations ex stipulatione in relation to the concept of the valid formation of contract. According to these newer attempts the explanation of the meaning of the Celsus’ phrase seems to be more reliable.