The article discusses the de lege ferenda proposals concerning the general principles of the impact of change of circumstances on obligations. The conducted analysis focuses on introduction to the Polish civil law of a statutory obligation to negotiate in good faith as well as prerequisites for liability for breach of this duty. The proposed liability may raise some doubts both in terms of its function and scope for compensation. The article proposes to apply the construction of liability of 'negative contractual interest' what is justified by the difference between positive and negative contractual interest and conclusions arising from the principle of private autonomy. The article argues that compensation of negative contractual interest means full compensation that does not include in its scope only positive contractual interest resulting from a negotiated agreement which was finally not concluded. The proposed liability might change a legal nature of 'negative contractual interest'. According to the novelization, this institution might be perceived as a compensation for loss of chances or as an aspect of causal relationship. However, under the Polish Civil Code, it should be rather defined as a statutory clarification of the source of the damage by reference to the behavior of the aggrieved party acting in trust for the perpetrator what is expressed in the content of existing legislation.