In its judgment dated 8 November 2018 (file no. I. ÚS 1283/16), the Constitutional Court explored the legal basis for so-called additional work. The issue at hand was whether work beyond the scope originally agreed on should be seen in the context of the original work contract or treated as a new independent performance (i.e. not one subject to the original contract). The court held that the question to be asked is whether this work could by its purpose and nature be seen as in the service of the originally agreed work. At the same time, a client who ordered certain work could not be made to pay for additional work outside the originally agreed scope even if the additional work was done as part of or in connection with the originally agreed work. The reason for this was that the client never ordered the work and might not even be interested in it. This rule applies even if the additional work increases the value of the final product.
In sum, if a contractor produces work of greater value as a result of its additional work, it may not claim the increased value as unjust enrichment because the work contract rules out such a claim.