Direct objects of any kind in Tunisian Arabic can be either unmarked or appear preceded by the particle 'fi'. The dissertation describes and analyzes this property of the language in a Generative framework. After a thorough description of the contexts in which the insertion of ‘fi' takes place, the thesis argues in favor of a semantic/syntactic analysis of the phenomenon which attributes to the particle ‘fi' the role of a case licensing prepositions whose insertion takes place in order to prevent a violation of the Case filter. Such a Case salvaging operation is illustrated to take place in contexts whereby uniform temporal binding throughout the event structure is prevented due to the presence of an intervening element endowed with an aspectual property. The analysis highlights the existence of a relation between the Case of a direct object and the temporal constituency of the event it partakes.