Restitution of retroactively terminated contracts

In case a contract is terminated retroactively, despite the exchange of performances has taken place, these performances must be returned. If the parties are able to return the performances in full, the unwinding of the conractual relationship does not propose a big problem. However, during the period between the performance and the return of the performance, there may have been some changes in the performance. The goods may have been destroyed, consumed or deteriorated. The obligor of restitution may have made some expenditures for the performance subject to restitution or, on the contrary, may have obtained some benefits from this performance. Or the performance may be an intangible performance such as a service or use. In all these cases, the question is how the unwinding of the contractual obligations should take place. Under our legal system, the provisions of restitution in wrongful possession or unjust enrichment are applied in the unwinding of contracts that are terminated with retroactive effect. In addition, the rules of contract law applicable to the unwinding procedure lack a detailed regulation. At this point, whether a regulation on a single unwinding regime is required, and if this question is answered in the affirmative, how this liquidation should take place, constitute the legal problem that this thesis tries to solve.