Unilateral amendment clauses in B2B contracts – key differences between Swiss and German law
This article examines the legal limitations of unilateral-amendment clauses in B2B contracts under Swiss and German law. It shows that Swiss law adopts a principle-based and comparatively liberal approach, which allows for unilateral amendments provided that the triggering circumstances and scope of possible changes are sufficiently determinable, the clause respects good faith, and it does not place the counterparty at the arbitrary discretion of the other party. The article compares the Swiss framework with the significantly more codified and restrictive German framework. Under German law, unilateral amendment clauses are subject to extensive transparency and fairness controls and, in the case of price adjustments, to the additional requirements of the Price Clause Act. Unilateral amendment clauses contained in General Terms and Conditions are further subject to stricter codified rules under German law, whereas Switzerland lacks a similar codified GTC regime. The analysis concludes with practical drafting considerations and advice on the choice of governing law in long-term commercial contracts.
Unilateral amendment clauses in B2B contracts – key differences between Swiss and German law
In long-term B2B commercial contracts, amendment clauses provide flexibility to make alterations to both performance and price. They allow companies to react quickly to market developments and regulatory changes and are therefore commonly included in long-term supply, licensing, franchising, or IT agreements. At the same time, such clauses can carry a substantial legal risk, especially if they are drafted too vaguely or grant one-sided discretion to a single party.
This article examines how unilateral amendment clauses are treated under Swiss and German law, highlighting the principles, constraints, and practical considerations that businesses should consider when drafting unilateral amendment clauses, particularly when including them in general terms and conditions (GTC, Allgemeine Geschäftsbedingungen).
I. Unilateral amendment clauses under Swiss law
Swiss law provides a comparatively flexible and liberal framework for contract amendment clauses. Freedom of contract is a central principle of Swiss private law (Art. 19 of the Swiss Code of Obligations, CO) and puts relatively few requirements to make contract clauses legally binding. Swiss law allows parties to bind themselves to conclude a future contract (Art. 22 CO), which logically includes the possibility of committing to future contractual amendments. Nevertheless, unilateral contract amendment clauses, especially when included in GTC, must adhere to a few constraints.
A. General principles
1. Determinability
The first limitation is the requirement of determinability (Bestimmtheitsgebot). As an expression of the general requirement of consensus under Art. 1 CO, the content of the contractual obligation must be at least determinable at the time of contract conclusion. According to case-law of the Swiss Federal Supreme Court (FSC), unilateral amendment clauses are only valid if both the triggering circumstances of a future amendment and the possible scope of the modification are at least determinable. A purely subjective determination of the adjustment is unacceptable, according to the jurisprudence of the FSC. The conditions that trigger an amendment and the scope of possible changes must be defined well enough so that both sides understand how the contract terms can be modified. This is typically not the case if a right to amend stipulates that it may be exercised to "safeguard legitimate interests".
Where a unilateral clause relates to the purchase price, the determinability requirement is further specified by Art. 184(3) CO. The purchase price, as an objectively essential element of a sales contract, must be either fixed or at least objectively determinable. A price is only considered determinable if it can be calculated based on objectively measurable criteria, such as an index, raw material prices or other verifiable parameters. Clauses that vaguely refer to "changed costs" or "market fluctuations" without specifying objective benchmarks or calculation methods typically do not meet this requirement. Accepted structures include allowing a narrowly limited degree of discretion to one party or a third-party determination.
If the determinability requirement is violated, the legal consequence is the invalidity of the amendment clause. The clause is void from the outset and cannot serve as a contractual basis for any unilateral modification. The remainder of the contract remains binding in its original form, but the party invoking the clause has no right to alter the contract unilaterally. Swiss courts will not correct an insufficiently precise amendment clause to make it workable, nor will they replace it with their own amendment mechanism. The lack of determinability constitutes a defect of consensus and therefore generally cannot be cured by judicial intervention.
2. Prohibition of excessive contractual binding
In addition to the requirement of determinability, unilateral amendment clauses must comply with Art. 27(2) CC, which prohibits excessive contractual binding (übermässige Bindung). This provision safeguards the future economic freedom of the contracting parties and prevents contractual arrangements that place one party at the arbitrary discretion of the other ("der Willkür eines anderen ausgeliefert"). Even where a clause is sufficiently determinable, it may not be permissible if it grants one party a broad and enduring power to modify the contract in a manner that effectively subjects the counterparty to unilateral control over essential elements of the contractual relationship. This concern is particularly pronounced in long-term contractual relationships, in situations of economic dependence, or where objectively essential contract elements such as price or core performance obligations are exposed to unilateral modification.
If an unilateral amendment clause results in an excessive contractual binding within the meaning of Art. 27(2) CC, the clause is unenforceable, while the remainder of the contract remains in force. Swiss law applies this consequence with restraint, and not every contractual imbalance triggers invalidity. A clause leading to contractual imbalance may remain valid but be subject to strict scrutiny when exercised. The existence of a termination right for the counterparty can attenuate the intensity of the binding, but it does not render an otherwise excessive clause permissible.
3. Good faith and abuse of rights
All contractual rights, including unilateral amendment rights, must be exercised in accordance with the principle of good faith and may not amount to an abuse of rights (Art. 2 Swiss Civil Code, CC). This requirement applies independently of the abstract validity of the amendment clause and governs the concrete exercise of the amendment right. Even where the parties have agreed to a unilateral amendment mechanism, the party empowered to modify the contract may only exercise this right in a reasonable and proportionate manner (nach billigem Ermessen). In particular, the amending party must avoid imposing unfair pressure or exploiting economic dependency. An amendment that is not objectively justified, that is disproportionate in scope, or that is imposed without adequate notice or explanation may be challenged as contrary to good faith.
If a unilateral amendment is exercised in violation of the principle of good faith or not in a reasonable and proportionate manner, this does not affect the validity of the amendment clause. Rather, only the specific amendment is ineffective and does not become binding on the counterparty, with the result that the contract continues to apply in its unamended form. Swiss courts, however, approach the finding of an abusive exercise of an otherwise valid amendment right with considerable restraint. Since corrective judicial intervention must not undermine the risk allocation agreed by the parties, high thresholds apply to any judicial interference based on an abuse of rights.
B. Control of unilateral amendment clauses in general terms and conditions
Where unilateral amendment clauses are contained in GTC, Swiss courts apply specific judicial control mechanisms developed in case-law to address the structural imbalance inherent in pre-formulated and unilaterally imposed contract terms. Although Swiss law does not provide for a codified GTC regime, the FSC has long recognised the need for heightened scrutiny when evaluating clauses in GTC. These corrective mechanisms operate both on the level of incorporation and interpretation.
At the level of incorporation, unilateral amendment clauses in GTC are subject to the rule of unusual clauses (Ungewöhnlichkeitsregel). Under this rule, clauses that are atypical for the relevant type of contract from a subjective and objective standpoint are excluded from the contract. This applies unless the counterparty was expressly made aware of the clause at the time of contract conclusion. Objective unusualness is assumed, particularly where a clause leads to a substantial alteration of the contractual character or departs markedly from the dispositive statutory model to the detriment of the adhering party. In the context of unilateral amendment clauses, this may be the case where one party is granted a broad right to unilaterally modify essential elements of the contractual relationship. If a clause is found to be unusual, the clause is ineffective, while the remainder of the contract continues to apply unchanged.
Even where a unilateral amendment clause has been validly incorporated into GTC, its wording remains subject to GTC-specific principles of interpretation (Auslegungskontrolle). GTC are interpreted according to the general rules of contractual interpretation but reflecting the trust principle from the perspective of an average contracting party in the relevant business sector. Where the wording of a clause is ambiguous or permits several reasonable interpretations, the ambiguity rule (Unklarheitenregel) applies. In case of doubt, the clause can be construed against the drafter of the GTC.
II. Unilateral contract amendment clauses under German law
German contract law imposes a far more structured and codified framework on unilateral contract amendment clauses than Swiss law. Although both legal systems pursue similar objectives (i.e. clarity, fairness in contracts and the avoidance of any excessive contractual binding), German law pursues these objectives through a specific set of statutory controls, in particular the rules on GTC under §§ 305 et seqq. of the German Civil Code (BGB) and the specific provisions of the Price Clause Act (Preisklauselgesetz, PrKG). These mechanisms together form a coherent system of ex ante control, which leaves less room for contractual experimentation than the more principle-based Swiss approach.
A. General principles
1. Determinability
§ 315 BGB embodies the fundamental principle that contractual performance may be left to the determination of one party or a third party only if the contract provides at least a framework of criteria that describe the scope of discretion. This applies where the determining party is empowered to interfere with the other party's legal position (e.g. if a company share may be withdrawn for compensation, the contract must establish calculation principles for such compensation). In the absence of sufficient contractual criteria, the agreement is invalid due to a lack of determinability (Bestimmtheitsgebot).
Where the parties use notions such as "usual", "appropriate", "reasonable" or "fair market value", German courts generally presume that the parties refer to an objectively ascertainable performance based on suitable comparative standards. In cases where the determinability criterion is not met, the performance may be determined directly by the court according to objective criteria.
2. Good faith
As in Switzerland, the principle of good faith governs both the drafting and the exercise of unilateral amendment rights. In German law, this principle is generally codified in § 242 BGB, and specifically by the rule on unilateral determination right in § 315(1) sentence 1 BGB. Where a contract authorises one party to unilaterally determine performance or adjust the contract price, § 315(1) sentence 1 BGB requires that such determination comply with an objective standard of equitable discretion (billiges Ermessen), considering the legitimate interests of both parties and the purpose of the contract. Any unilateral determination made by one party exercising its contractual right is only legally binding if it conforms with the standard of equitable discretion.
§ 315(3) BGB gives courts the right to intervene and correct an excessive or unjustified exercise of unilateral amendment rights. In this respect, German law goes further than Swiss law, since courts are empowered to substitute their own equitable determination instead of the party exercising the unilateral right if a violation of the principle of good faith is found.
B. Control of unilateral amendment clauses in general terms and conditions
Under German law, where unilateral amendment clauses are included in GTC, they are subject to the additional more stringent controls of §§ 305 et seqq. BGB.
The starting point for assessing unilateral amendment clauses in GTC is the transparency requirement of § 307(1) sentence 2 BGB, which obliges the drafter of GTC to formulate clauses in a manner that enables the average contracting party to understand both their content and economic implications. This requirement applies equally in B2C and B2B transactions. Unilateral amendment clauses must specify the following:
- the circumstances that may trigger an amendment;
- the method by which the revised performance or price will be determined; and
- the foreseeable range of possible adjustments.
Furthermore, as in Switzerland, unusual and surprising clauses do not become part of the contract (§305c BGB).
Under § 307(1) sentence 1 BGB, a clause contained in GTC is invalid if it unreasonably disadvantages the other contracting party by upsetting the contractual balance of rights and obligations in a manner incompatible with fundamental statutory principles. In the context of unilateral price adjustment clauses, such clauses must preserve the original equivalence between performance and counter-performance and may not be used to shift the economic risk of the contract unilaterally to the counterparty.
In particular, price adjustment clauses may not allow the drafting party to pass on cost increases without a corresponding obligation to pass on cost reductions within a reasonable period. This requirement is referred to as the Saldierungsgrundsatz. Clauses that permit only upward price adjustments or enable the supplier to generate additional profit beyond compensating for actual cost increases are considered to unreasonably disadvantage the counterparty and are invalid under § 307(1) sentence 1 BGB.
§ 308 No. 4 BGB further restricts clauses in GTC that reserve the right to modify contractual performance. Such clauses are permissible only if there is an objective justification for the modification, the modification is reasonable for the other party, and an appropriate period of prior notice is granted. Standard terms that authorise changes discretionary of one party are invalid.
Clauses violating §§ 307–309 BGB are invalid from the outset (ex tunc). The remainder of the contract remains binding pursuant to § 306 BGB, unless it is evident that the parties would not have entered into the contract without the invalid clause.
C. Price adjustment clauses under the Preisklauselgesetz (PrKG)
The PrKG imposes an additional layer of regulation for price adjustment clauses. The PrKG applies to B2B contracts whenever a monetary obligation is linked to a price-adjustment clause, provided that the clause sets the payment amount based on objectively determinable criteria. The PrKG requires that the affected party ascertain the relevant cost components, their weighting, and their impact on the final price. According to § 1(1) PrKG, contractual payment obligations may not be automatically linked to the price or value of unrelated goods or services. Only narrowly defined exceptions are permitted, such as performance reservation clauses, index clauses based on comparable goods or services, or cost-element clauses tied directly to the supplier’s actual procurement costs. German courts interpret the exception for comparable indices restrictively. For example, linking electricity prices to wage indices or to unrelated commodity prices has been held to violate the PrKG. The courts require that the relevant cost elements be transparent, ascertainable by the customer, and properly weighted. Even where a clause complies with the PrKG, it remains subject to control under § 307 BGB, as the two regimes apply in parallel.
Under § 8 PrKG, an unlawful price clause remains conditionally valid until a court determines its invalidity, and the invalidity takes effect only for the future (ex nunc). Payments made before a judicial finding of invalidity cannot be reclaimed.
III. Conclusions
In conclusion, while both Swiss and German law recognise the importance of amendment clauses in commercial contracts by allowing them in general, they take quite different approaches in the clauses’ examination. Swiss law remains comparatively flexible because it does not have a codified GTC regime and relies mainly on general contract law principles and judicially mandated control mechanisms. By contrast, German law imposes a more codified and specific legal framework for GTC, which gives courts a more far-reaching toolkit to review amendment clauses, including in the B2B setting.
From a practical perspective, the choice of governing law requires businesses to weigh planning certainty against contractual flexibility. When drafting B2B contracts under German law, parties must be aware that any unilateral amendment clauses contained in GTC will be measured against the statutory standards of §§ 305 et seqq. BGB, which cannot be contractually excluded in advance. Price adjustment mechanisms may additionally fall within the scope of the PrKG. Whether the PrKG applies similarly does not depend on party choice, but on the structure and effect of the clause. This regulatory density limits contractual freedom but enhances predictability and limits the discretion of the party invoking the amendment clause.
Under Swiss law, courts are generally more deferential to the autonomy of commercial parties. This means that unilateral amendment clauses can be drafted more broadly, provided that the prerequisites and scope of amendments are clearly defined and the clause does not effectively place the counterparty at the other party’s discretion. In the GTC context, Swiss protection is achieved mainly through incorporation and interpretation control. Unusual clauses may fail to become part of the contract at all, and unclear wording is construed against the drafter. This regime may therefore suit parties that want contractual flexibility, but it also means that more risk is managed through careful drafting and the general principles applied ex post.
