Author(s) Helton Salomão Tavares de Carvalho
Advisor(s) Fernando Gravato Morais
Year 2017

Synopsis We consider to devide the work into five chapters. In the first place, the system of the purchase and sale agreement in the portuguese Civil Code will be analyzed, using the vicissitudes that this contractual type entails, due to the considerations included in the portuguese legal order. Next, in the light of the same legal system, the purpose of the study is to understand the influence of the characteristics of contract on the legal position of the contractual parties, as regards the legitimacy and the capacity and suitability of the negotiating object. In addition, stablish the bridge with the regime of nulity of the sale of another´s cisa. In the second chapter, consideration will be given to the nullity of the sale thirdparty goods, wich, even if this same act of disposition is condidered null and void allows for the possibility of convalidation. In consequence of this, it turns out that this nullity is considered atypical or mixed according to the dominat doctrinal understanding. However, we will not, therefore, make a comment with recourse to comparative law, namely in Germany where the sale of foreign goods is valid and also, under domestic law, to compare the commercial regime of alienation of something that is valid, but with this the effects do not differ much from the nullity of the civil sale, when admissible the validation. If the sale is valid in the commercial regime, the possibility of the owner´s claim of nullity is not called into question. Next, in the third chapter, we will examine the principal of good faith and its consequence for arguing for nullity between the lender and the buyer of an alien´s property by extending this regime to pré-contractual liability. Before we enter into the scope of the regime of the nullity argument, we will in the fourth chapter proceed to the study of some contractual types that are approximate with the sale of foreign goods, but divergent by the acceptance of their validity, it´s a question of the sale of future goods, contract-promise of alienation of third party goods, tabular acquisition (protection of the acquirer by the rules of registration and in good faith) and the commercial regime of the sale of ferign goods. Finnaly, in the fifth chapter, after exercising all these «pressupositions» we are in a better position to address the matter regardind the possibility of arguing for nullity between the contractors that is, in the internal relation and on the other hand in the external relation in wich it´s for the real owner to be or not to be entitled to rely on the nullity of the purchase and sale. We shall conclude by verifying that the verus dominus is legitimate, in addition to being able to bring an action for restitution of ownership and / or claim of property, likewise may invoke the nullity of the sale of something that is his property. No legal obsolete can be envisaged for this posibility.

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