OGH: When Are Expert Reports Binding?

Jun 4, 2026 Benn-Ibler Rechtsanwälte

The Austrian Supreme Court (Oberster Gerichtshof, hereinafter OGH) examined the issue of determining when a pre-litigation expert report should be classified as a binding arbitration report. This matter originated from a disagreement concerning supplementary claims related to the refurbishment of a residential complex.

In the case at hand, the claimant had been hired to replace windows and subsequently requested further compensation for plastering and soffit work, contending that these services were not part of the initial specification. The respondent, however, cited a binding arbitration report obtained during the construction project, which dismissed the claim for additional costs.

Arbitration reports may be submitted regardless of format

The OGH affirmed the rulings of the lower courts, determining that a valid arbitration agreement had been established between the parties. The critical consideration was not the term used, but rather whether the parties intended to assign a third party the authority to make binding determinations regarding specific facts or issues related to performance.

In this particular instance, following a dispute, the parties reached an agreement to have an independent expert provide a binding clarification of the contested issue. The OGH held that the expert’s personal perspective on whether his work constituted an ‘arbitration report’ was immaterial. Additionally, arbitration agreements are not governed by specific formal requirements.

Interpretation of the specifications is decisive

In its interpretation of the specifications, the OGH relied on the objective viewpoint of an experienced contractor. The expert opinion indicated that an informed contractor should have recognised that the required reveal and plastering works were included in the tendered scope of services and, consequently, could not be billed separately.

Additionally, arguments presented by the claimant for the first time during the appeal proceedings were excluded in accordance with the prohibition against raising new matters.

High invalidity threshold

The OGH concluded by highlighting that expert opinions are set aside only under exceptional circumstances, such as cases of significant unfairness or clear error. A simple difference in technical evaluation does not warrant such disregard.

OGH 4 Ob 57/25y (26 March 2026)