Oral Modification of Written Wage Criteria in Employment Contract

The dispute concerned whether pre-agreed written criteria for calculating wages, established within an employment contract, could be subsequently modified by a later oral agreement, despite a contractual stipulation for written form regarding these criteria. The lower court dismissed the claim because it deemed the written form requirement applicable to amendments, thus refusing to examine the alleged oral modification. The appellate court overturned this, reasoning that while the written form was agreed upon for setting the initial performance targets, a claim regarding a subsequent modification of an established wage claim cannot be rendered inadmissible based on the lack of written form for the modification itself, as the underlying wage claim is of mandatory nature; therefore, the initial written agreement on criteria serves merely as proof, and the party asserting a subsequent oral change must be permitted to provide evidence for that later agreement.