Förutsättningsläran - En rättsregel i svensk rätt?

Sammanfattning: Summary Problems arising in contractual relationships appear to be a common occurrence in most contractual relationships. This can either be due to the facts which the parties have not foreseen at the conclusion of the contract, or a result of a development of events differently from what the parties have expected. To be able to take into account all possible relevant circumstances at the conclusion of the agreement, or to anticipate event developments thereafter as a contracting party in connection with the conclusion of an agreement, is impossible. The regulated area regarding mistakes or changed circumstances only treats certain types of conditions and is not exhaustive. It can happen that one of the parties wants to withdraw from the contract because the transaction, due to unknown or unforeseen circumstances, becomes less favorable or more difficult than the party anticipated. The basic principle of contract law that contracts must be fulfilled, pacta sunt servanda, is still valid; this means that the contract is binding, regardless of whether these conditions are deficient. Most contracts are based on some kind of conditions (förutsättningar). The party who enters into a contract on certain conditions also expects that these conditions will be fulfilled. Problems in contractual relationships are often discovered when some unknown or unforeseen circumstance causes the obligations to become less favorable or more difficult than anticipated. Such agreements may appear as unjust, unfair, or otherwise unreasonable to uphold. To demand the fulfillment of such an agreement can then be regarded as unreasonable. In exceptional circumstances, a party may be exempted from its contractual obligations by means of, e.g. invalidity rules. Agreements can also be declared inactive with reference to the conclusion of the agreement under incorrect conditions. A situation may occur in which a party, claiming a mistaken assumption or change in circumstances, wants to withdraw from the agreement, even-if the situation that has occured is not explicitly regulated in the contract. In such cases the doctrine of failed assumptions (förutsättningsläran) might be invoked to invalidate the contract.