What is the function of an expert?
Under the German Code of Civil Procedure (Zivilprozessbuch, "ZPO"), the role of an expert is to provide the court with a neutral assessment based on his knowledge as an expert against the background of certain specified facts. The expert opinion is valid as formal evidence (Sections 402 et seq. ZPO), which the judge will take into account when reaching his decision. The expert’s opinion is, however, not formally binding on the judge. The court remains free to evaluate any and all pieces of evidence submitted by each party and thus remains the sole and exclusive decision maker on the alleged facts which are the subject matter of the expert evidence. By appointing an expert, the court does not delegate any aspect of its power to a third party, but rather merely shares in the expert's specific knowledge.
Who can be an expert and how are experts appointed?
Authorities, in particular public authorities, as well as individuals, can be appointed as experts in court proceedings. Such appointment is made by the court and/or jointly by the parties by a consensual decision. Expert evidence which is unilaterally introduced by one party, however, is considered a mere party assertion.
The court can consider an individual's expertise to be either "expert evidence" or "documentary evidence". An authority's expertise, however, is always considered to be expert evidence by the court. In addition, a research institute's expert opinion can also be introduced to the court as expert evidence.
In order to assist the court in finding qualified experts, it is open to public authorities to appoint experts on specific topics on a general basis (e.g. motor vehicle experts, building craft experts). When choosing an expert, the courts are required by law to prioritise such so-called "publicly appointed" experts (if available), (Section 404 para. 2 ZPO).
How is expert evidence provided?
It is up to the court whether it requests a written or an oral expert opinion in any given case, however, courts tend to favour the use of written expert evidence. In cases where a written expert report is requested, it is still open to the court to summon the expert for further explanation.
Can the court control the expert?
Since the expert evidence is procedurally regarded as a neutral opinion, the court is not allowed to control or influence the results of the expert's assessment. Under Section 404a ZPO, however, the court is entitled to control the formal circumstances of the expert's assessment to a certain extent. In this context, the court is, in particular, entitled to define the type and the scope of the expert evidence, as well as to determine which facts the expert evidence is to be based upon and whether/to what extent the expert may contact the parties for the purpose of preparing his evidence.
Rejection of an expert
Rejection of an expert follows the same rules as the rejection of a judge (Sections 41, 42 ZPO). In particular:
- The court must reject an expert who is party to the court proceedings or who stands as a co-debtor or co-beneficiary to one of the parties or who is or has been married to one of the parties;
- It is in the court's discretion to reject an expert in any case where there is a concern of prejudice.