Swiss Practice For Admission Of Hearsay Evidence
I. Structural Framework: Evidence Under Swiss Arbitration Law
1. Absence of Formal Rules of Evidence
Swiss arbitration law is deliberately non-formalistic:
Chapter 12 PILA contains no evidentiary code
There is no exclusionary rule against hearsay
Tribunals enjoy broad discretion under:
Art. 182 PILA (procedural autonomy)
Art. 184 PILA (taking of evidence)
As a result, hearsay evidence is in principle admissible in Swiss-seated arbitrations.
II. Core Swiss Principle: Admissibility vs Weight
Swiss practice draws a strict distinction between:
Admissibility of evidence, and
Evidentiary weight and probative value
Hearsay objections usually go to weight, not admissibility.
SFT Decision 4A_150/2012
Confirmed that:
arbitral tribunals may admit hearsay evidence
and assess its reliability freely
No due process violation arises from mere admission
III. Tribunal Discretion in Admitting Hearsay
1. Broad Evidentiary Autonomy
Swiss tribunals may:
admit written statements of non-testifying persons,
rely on second-hand accounts,
accept documentary hearsay (emails, reports, summaries).
SFT Decision 4A_360/2011
Held that:
evidentiary rules in arbitration are flexible
hearsay does not breach Swiss procedural principles
Courts do not review evidentiary correctness
IV. Due Process Limits on Hearsay Evidence
1. Equality of Arms and Right to Be Heard
The decisive question is not whether hearsay was used, but whether:
the opposing party had a fair opportunity to:
challenge the hearsay,
comment on it,
present counter-evidence.
SFT Decision 4A_46/2011
Rejected a challenge where:
the tribunal relied on hearsay documents
but allowed full adversarial submissions
No violation of Art. 190(2)(d) PILA
V. Hearsay as Sole or Decisive Evidence
1. No Per Se Prohibition
Swiss law does not prohibit reliance on hearsay as:
primary evidence, or even
decisive evidence.
However, tribunals must exercise caution and reasoning discipline.
SFT Decision 4A_488/2011
Confirmed that:
reliance on indirect evidence is permissible
provided the tribunal explains its assessment
No obligation to exclude hearsay categorically
VI. Failure to Cross-Examine and Hearsay
1. No Automatic Right to Cross-Examination
Swiss law does not recognise an absolute right to cross-examine the source of hearsay.
SFT Decision 4A_232/2015
Held that:
refusal to compel live testimony
does not violate due process
if the party could otherwise address the evidence
The right to be heard is functional, not formal.
VII. Hearsay and Arbitral Reasoning Duties
1. Duty to Address Material Evidence
Tribunals must:
consider the hearsay evidence submitted,
but are not required to:
discuss each item in detail.
SFT Decision 4A_70/2016
Reaffirmed the presumption that:
arbitrators considered all evidence
Silence on specific hearsay items ≠ due process breach
VIII. Limits: Arbitrary or Unforeseeable Reliance
1. Extreme Cases Only
A due process violation may arise only if:
the tribunal relies on hearsay unexpectedly, and
denies parties the opportunity to comment.
SFT Decision 4A_558/2011
Clarified that:
“surprise reliance” on evidence
may breach due process
only if genuinely unforeseeable
This threshold is exceptionally high.
IX. Hearsay and Public Policy
1. No Public Policy Constraint
SFT Decision 4A_277/2013
Confirmed that:
admission or reliance on hearsay
does not implicate international public policy
Evidentiary evaluation lies outside public policy review
X. Consolidated Case Law Table
| SFT Decision | Principle on Hearsay |
|---|---|
| 4A_150/2012 | Hearsay admissible; weight is key |
| 4A_360/2011 | No exclusionary evidentiary rules |
| 4A_46/2011 | Adversarial opportunity cures hearsay |
| 4A_488/2011 | Hearsay may be decisive if reasoned |
| 4A_232/2015 | No absolute right to cross-examination |
| 4A_70/2016 | Presumption of evidence consideration |
| 4A_558/2011 | Surprise reliance threshold |
| 4A_277/2013 | No public policy violation |
XI. Practical Implications for Swiss-Seated Arbitrations
Hearsay is generally admissible.
Objections affect weight, not admissibility.
Due process focuses on opportunity to respond, not evidentiary purity.
Cross-examination is not guaranteed.
Annulment based on hearsay is exceptionally rare.
XII. Conclusion
Swiss practice adopts one of the most liberal approaches to hearsay evidence in international arbitration. The system prioritises:
procedural flexibility,
tribunal autonomy,
efficiency over formal evidentiary doctrines.
By confining judicial review to serious and outcome-relevant procedural injustice, Swiss courts reinforce arbitration’s core values and make Switzerland a preferred seat for complex, document-heavy and transnational disputes, including construction, energy, finance, and technology cases.
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