In its decision of 18 February 2020, the Swiss Federal Supreme Court (SFSC) reiterated its position that Swiss procedural law requires a concrete substantiation of the facts underlying a party’s claim: a general reference to a detailed expert opinion was considered as insufficient substantiation (Case No. 4A_445/2019 (in German)). Below, we will provide a case summary and a short overview on the particularly rigid substantiation duty under the Swiss civil procedure rules.

I.        The Swiss substantiation duty

As a specialty in Swiss procedural law compared to other European civil law countries (e.g., Germany), the parties are subject to a rigid duty to substantiate their facts. According to settled case law, at first, a fact only needs to be asserted in its essential features or contours in a way that corresponds to an ordinary statement. However, the assertion of a fact must be formulated so concretely that a substantiated denial by the respondent is possible. Only in the event that the opposing party denies the asserted facts, a burden of substantiation beyond the burden of assertion applies. The arguments must then be presented not only in their basic framework but also broken down into individual facts in such a comprehensive and clear manner that evidence can be taken or counterevidence can be presented. The obligation to substantiate is thus conceptually placed before the evidentiary phase of the proceedings and must make the taking of evidence possible. The correctness of an assertion itself is irrelevant to the question of sufficient substantiation. The truthfulness of a factual argumentation is subsequently clarified in the evidentiary phase of the proceedings.

The purpose of this requirement is to enable the court to identify the facts on which a claimant relies and to determine how the claimant intends to prove such facts. Moreover, it gives a respondent the possibility to determine against which specific allegations it must defend itself.

In addition, Swiss case law requires that the burden of assertion and substantiation must in principle be complied with in the parties’ submissions and does not allow a mere, blanket reference to exhibits to suffice. The ratio behind this requirement is that neither the court nor the other party shall have to gather the factual allegations from the exhibits. Especially in the case of complex factual situations it is often unclear on what basis the findings in an expert opinion are based and there may thus be a lack of clear attribution of evidence to concrete facts.

II.       A general reference to an expert opinion is not a sufficient substantiation

The reported decision was preceded by a first instance proceeding before a lower Swiss court during which the claimant filed a detailed 32-page expert opinion. The factual circumstances and findings contained in the expert opinion were not repeated by the claimant in its submission; the claimant only generally referred to them. The lower court did not consider the expert opinion because of the insufficient substantiation of its factual arguments.

The SFSC consequently found that a global reference to documents on file does in principle not satisfy the requirements of assertion and substantiation, unless the other party and the court nevertheless obtain the necessary information in such a way that incorporation into the submission appears to be a mere copy-paste exercise. However, it is a duty of the party filing an expert opinion to show to what extent the expert’s factual assertions were so self-explanatory that a reproduction of the essential content in the legal document would have meant a mere copy-paste exercise.

As the highest Swiss court specified, even a clear structure of the expert opinion does not alter the fact that all relevant information contained therein must be incorporated into the submission and explained by the party.

Accordingly, the SFSC upheld the decision of the lower instances not to consider claimant’s claim because of insufficient substantiation.

III.      Key takeaways

Against this background, a reference to exhibits or expert opinions in submissions may be admissible under certain circumstances. However, a reference must not result in the other party and the court having to pick the facts from the exhibit or expert opinions themselves. It is therefore not sufficient that an exhibit contains a relevant information in some form. The information must be easily accessible without any room for interpretation. The reference in the party’s submission must specifically refer to a certain exhibit and such reference must clearly indicate which parts of the document are to be considered as a fact supporting the party’s claim. An unproblematic access to an exhibit by the court is guaranteed only if such exhibit is self-explanatory and contains exactly the information required (or specified in the submission). In such case, however, the party filing the document must outline the reasons why a detailed reproduction of the exhibit or the expert opinion would lead to a mere copy-paste exercise.


Dr. Valentina Hirsiger is senior associate in Baker McKenzie’s Arbitration and Litigation Group in Zurich. Prior to joining the Firm as an associate in 2016, Valentina was an associate lecturer and research assistant at the University of Zurich and was awarded the Walter Hug Prize for her doctoral thesis on arbitration clauses in articles of association of Swiss corporations. Since 2023, Valentina has acted as a part-time judge at the Princely Supreme Court in Liechtenstein. Valentina advises parties in the field of dispute resolution and general contract law, with a focus on national and international disputes in commercial, construction and corporate law. She has represented parties in various commercial disputes before both international arbitral tribunals and state courts and regularly advises clients on project and contract management and dispute avoidance.


Lukas Innerebner is a trainee lawyer in the Arbitration and Litigation Group of Baker McKenzie in Zurich.