Aliud in sale contracts according to Turkish Law and Vienna Sales Convention

The concept of aliud expresses the situations where one's delivery of a commodity which is different from the one stipulated between the parties. Determining the rights of obligee against obligor's behavior is one of the most intricate problem of law of obligations. With the aim of ascertaining the interests of parties, the boundries of the concept is attempted to be determined in view of its similarity to the concept of defect. Accordingly, in the doctrine, various opinions have been put forward. There are two approaches on this issue. According to first of these, defects liability law should be applied. The second approach asserts that the provisions related to default of debtor should be applied. The prevailing position under the first approach distinguishes between generic and specific obligations and asserts that aliud is acceptable only when the generic obligations are at stake. The second approach which is argued for in this dissertation asserts that the provisions related to default of debtor should be applied without distinguish between generic and specific obligations. According to this view, aliud is conceptually distinct from defect. Unless a specific regulation is put into action about aliud, the standing provisions related to default of debtor should be applicable. In the first part of this study, the main points aforementioned approaches are attempted to be explained in view of the interests of parties. The results are compared with the decisions of the Swiss Federal Court and the T urkish Supreme Court as far as possible. Starting from fourth title the CISG's approach to delivery of aliud is attempted to be explained in the light of the submitted opinions.