3. Gap-filling

The logical result of the fact that the CISG only regulates certain matters is the question how to deal with not expressly regulated.


a. External Gaps

The solution is pretty straightforward for matters not governed by the CISG, so called external gaps. Here, the Convention does not apply and the international private law of the forum defines the applicable domestic law.


b. Internal Gaps

But also for matters governed by the CISG, there is not always an express solution to be found in the provisions of the CISG. These so called internal gaps are dealt with by Art. 7(2):

(2) Questions concerning matters governed by this Convention which are not expressly settled in it are to be settled in conformity with the general principles on which it is based or, in the absence of such principles, in conformity with the law applicable by virtue of the rules of private international law.

This provision contains a two-tiered approach to fill internal gaps. Primarily, the general principles the CISG is based on are to be relied upon. Only if those general principles do no contain an adequate solution, recourse can be had to domestic law.


aa. General Principles

Given the difficulties to address all possible legal questions in a concise statutory text the CISG’s aim of unification would be severely undermined if all matters not expressly dealt with were governed by non-unified law. Thus, before falling back to domestic law the general principles the CISG is based upon have to be turned to.

These general principles have to be distilled from the provisions of the Convention itself. It is therefore as impossible as unnecessary to draw a clear line between the interpretation of the CISG and the filling of gaps by recourse to the general principles the Convention is based on. Examples for principles underlying the CISG are:

  • Primacy of party autonomy
  • Freedom of form
  • Prohibition of contradictory behavior (estoppel / prohibition of venire contra factum proprium)
  • Principle of upholding the contract (favor contractus)
  • Principle of full compensation of damages
  • Obligation to mitigate damages and other disadvantages
  • Allocation of the burden of proof to the party who relies on the fact
  • Observance of good faith and fair dealings (disputed)


bb. Domestic Law

The CISG does not define which domestic law is to be applied. This is the task of the rules of international private law of the forum respectively the arbitration rules agreed upon by the parties or the lex arbitri.

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Last modified: Thursday, 22 October 2015, 4:41 PM