Abstract
This article aims synthetically to refer to discussion between Polish academic-lawyers about the controversies regarding to reduction of a specified sum in ?agreed or stipulated payment for non-performance? in art. 484 § 2 of Polish Civil Code. These conclusions, resulting from the analysis of Polish private law - will be referring to the same reduction-clause in three selected acts of contracts model law: UNIDROIT Principles of International Commercial Contracts, the Principles of European Contract Law and the Draft Common Frame of Reference. The last part of this article contains the conclusions de lege ferenda from comparative analysis.