Battle of the Forms under the Vienna Sales Convention: which GTCs apply?

Published on 14 December 2025 · Last updated 24 October 2026

The battle of forms under the Vienna Sales Convention (CISG) is the question of which general terms and conditions apply when buyer and seller each refer to their own. The CISG has no specific rule for this. Article 19 CISG points to the last shot rule, while the CISG Advisory Council favours the knock-out rule. Under Dutch domestic law, the first reference in principle prevails, unless the second party expressly rejects the terms referred to first (Article 6:225(3) Dutch Civil Code).

Many international sales of goods fall under the Vienna Sales Convention. It applies to contracts for the sale of goods between parties whose places of business are in different contracting states, or where the rules of private international law lead to the law of a contracting state (Article 1(1) CISG). Purchases for personal, family or household use are in principle excluded (Article 2(a)). If the CISG applies, its rules on the formation of the contract decide which general terms apply, and Article 6:225(3) of the Dutch Civil Code does not.

What does the battle of forms mean under the Vienna Sales Convention?

The battle of forms arises when both contracting parties refer to their own general terms and conditions upon concluding an agreement, while these conditions differ substantively from each other.

In international trade, professional parties almost invariably maintain their own general terms and conditions. A Dutch exporter, for example, applies delivery conditions with limited liability, whereas a German purchaser prefers purchase conditions with extensive warranties. Both parties reference these conditions in quotations, order confirmations, and invoices. Consequently, uncertainty arises about which set of conditions governs the agreement.

The economic stakes are considerable. General purchase conditions typically contain strict delivery deadlines and broad liability provisions. Delivery conditions, conversely, offer flexibility in delivery and limit liability to direct damages. In disputes, the difference between both sets of conditions can determine whether a damage claim of €50,000 succeeds or fails entirely.

When Does the Vienna Sales Convention Apply to Your Agreement?

The Vienna Sales Convention applies to international sales of goods between parties whose places of business are in different contracting states, unless the parties have excluded it (Articles 1 and 6 CISG).

According to the UNCITRAL status page, 97 states are party to the CISG (October 2026), including the Netherlands (in force since 1 January 1992), Germany, France, China and the United States. When a Dutch company sells goods to a buyer in another contracting state, the CISG applies unless it has been excluded. Its rules on the formation of the contract (Articles 14 to 24 CISG) determine when an agreement is concluded and which terms form part of it.

Parties can exclude the CISG (Article 6 CISG). A choice of the law of a contracting state, such as Dutch law, generally does not exclude it, because the CISG is part of that law. Use an explicit exclusion clause instead. If both sets of general terms exclude the CISG, that exclusion is common to both sets, and under the knock-out approach the CISG would then be excluded.

How does the knock-out rule work under the Vienna Sales Convention?

The knock out rule dictates that conflicting provisions in the general terms and conditions of both parties do not become part of the agreement, leaving only matching provisions in effect.

The CISG Advisory Council, an international expert group on the Vienna Sales Convention, favours the knock-out rule in Opinion No. 13 (2013), Rule 10. A contract is then concluded on the basis of the negotiated terms and the standard terms that are common in substance, unless one party clearly indicates in advance, or objects later without undue delay, that it does not want a contract on that basis. The Opinion is not binding. It notes that most commentators and court decisions favour the knock-out rule, but that the last shot rule also has support. Under Dutch domestic law, by contrast, the first reference in principle prevails (Article 6:225(3) Dutch Civil Code).

In practice, this means that when the seller limits liability to €10,000 and the buyer demands unlimited liability, neither provision applies. The Vienna Sales Convention then fills this gap with its own provisions on damages: compensation for the loss, including loss of profit, limited to what the party in breach foresaw or ought to have foreseen when the contract was concluded (Article 74 CISG). These Convention provisions typically offer sellers less protection than their own delivery conditions would provide.

What are the consequences of conflicting conditions under the Vienna Sales Convention?

If a court applies the knock-out rule to conflicting general conditions under the Vienna Sales Convention, businesses fall back on Convention provisions or supplementary national law, potentially causing undesirable legal consequences.

Take an example. A Dutch machinery manufacturer supplies heat exchanger tubes to a German buyer. Both parties refer to their own terms, with different liability provisions. The tubes prove defective, and the buyer incurs substantial costs for investigation, replacement and penalties towards its own customer. If the court applies the knock-out rule, neither party’s liability provision applies.

The claim is then assessed under the damages rules of the Vienna Sales Convention (Article 74 CISG). Those rules can allow broader compensation than many standard delivery conditions. The seller cannot rely on its exemption clause, and the buyer cannot rely on its extended warranty provisions. If the court applies the last shot rule instead, the terms of the party that referred to its terms last may apply.

How Does the Knock Out Rule Differ from Dutch Domestic Law?

The Dutch first shot rule in principle lets the first reference to general conditions prevail, whereas the knock out rule eliminates both conflicting conditions and refers parties back to supplementary law.

Article 6:225(3) of the Dutch Civil Code provides that, if offer and acceptance refer to different general terms, the second reference has no effect unless it also expressly rejects the applicability of the terms referred to first. In principle, the terms of the party that referred to its terms first then apply. This rule only applies if Dutch law governs the contract and the CISG does not apply.

The knock out rule creates a different situation altogether. Neither party wins automatically. Provisions that substantively correspond, such as payment terms of 30 days, remain effective. Whether a matching forum clause is valid is decided under the rules on jurisdiction, such as Article 25 of the Brussels I bis Regulation. Conflicting provisions regarding liability, warranties, or delivery conditions disappear from the agreement. Enterprises thereby lose the protection their conditions intended to provide.

What are the requirements for incorporating general terms under the Vienna Sales Convention?

According to the CISG Advisory Council, general terms and conditions become part of the agreement under the Vienna Sales Convention when parties consent to incorporation and the counterparty has had reasonable opportunity to take notice of the conditions.

Article 8 of the Vienna Sales Convention determines how statements and conduct of the parties must be interpreted. Under Article 9, the parties are also bound by usages they have agreed to and by practices established between them. Tacit consent may suffice for incorporation. When a buyer places orders for years referencing delivery conditions without protest, the supplier may be able to argue that the conditions have been accepted. Terms that are first sent after the contract was concluded, for example on an invoice, are in principle not incorporated, unless the parties agree to modify the contract (CISG Advisory Council Opinion No. 13, Rule 4).

The second requirement concerns accessibility. The other party must have had a reasonable opportunity to take notice of the terms. According to the CISG Advisory Council, a reference to terms on a website can be enough if the terms were accessible at the time of contracting (Opinion No. 13, Rule 3 and comment 3.4), but some courts are stricter. Sending the terms by email or attaching them to the quotation strengthens your position considerably.

The CISG does not govern whether a clause is valid (Article 4(a) CISG). That is a question for the applicable national law. If Dutch law applies, the Dutch rules on unreasonably onerous clauses (Articles 6:231 to 6:247 Dutch Civil Code) do not apply between businesses that are not both established in the Netherlands (Article 6:247(2)). A clause can then still be set aside, in particular if applying it would be unacceptable by standards of reasonableness and fairness (Article 6:248(2)).

Which law fills the gaps left by the Vienna Sales Convention?

Matters governed by the CISG but not expressly settled in it are decided according to its general principles and, failing those, under the law applicable by virtue of the rules of private international law (Article 7(2) CISG). For matters outside the CISG, the applicable national law applies directly.

If the knock-out rule removes provisions and the CISG does not answer the question, national law fills the gap. A court in an EU Member State determines that law under the Rome I Regulation. Without a valid choice of law, a contract for the sale of goods is in principle governed by the law of the country where the seller has its habitual residence (Articles 3 and 4(1)(a) Rome I). For a company, that is its place of central administration or, if the contract is concluded in the course of the operations of a branch or other establishment, or is to be performed by it, the place of that establishment (Article 19(1) and (2) Rome I). The law of another country applies if the contract is manifestly more closely connected with that country (Article 4(3) Rome I). A Dutch seller without a different choice of law will therefore usually see Dutch law fill the gaps.

Jurisdiction is a separate question. The applicable law does not determine which court is competent. That follows from a forum clause or from the rules on jurisdiction, such as the Brussels I bis Regulation within the EU.

How can you limit the risks of a battle of forms in international trade?

Enterprises limit risks in international trade by explicitly agreeing on one set of conditions, expressly rejecting the counterparty’s conditions, and recording the choice of law in the main contract.

The battle of forms arises because parties pay insufficient attention to the applicability of conditions during negotiations. Professional purchasers and sellers must actively discuss which conditions apply. An explicit provision in the main contract stating that only the conditions of party A apply helps prevent disputes.

Rejecting the other party’s terms clearly is essential. Under Dutch domestic law, a second reference only has effect if it expressly rejects the terms referred to first (Article 6:225(3) Dutch Civil Code). Under the CISG, Rule 10 of Opinion No. 13 allows a party to avoid a contract on the knock-out basis by clearly indicating in advance, or objecting without undue delay, that it does not want to be bound on that basis. Whether a standard defence clause in your own terms is enough is uncertain. A specific rejection in the main contract or accompanying correspondence, naming the terms rejected, is safer.

Do you want certainty about the applicability of your general terms and conditions in international trade? Our specialised lawyers in Amsterdam analyse your contractual position and advise on risk limitation for cross-border agreements.

What does the last shot rule mean under the Vienna Sales Convention?

The last shot rule, under which the last referenced conditions apply, is sometimes derived from the text of Article 19 of the Vienna Sales Convention. The CISG Advisory Council prefers the knock-out rule, but courts are not bound by its opinions.

Under Article 19(1) CISG, a reply to an offer that purports to be an acceptance but contains additions, limitations or other modifications is a rejection of the offer and a counter-offer. If the additions or modifications do not materially alter the terms of the offer, the reply is nevertheless an acceptance, unless the offeror objects without undue delay (Article 19(2)). Different terms on, among other things, liability and the settlement of disputes are considered material (Article 19(3)). If the other party then performs, for example by shipping the goods or paying the price, that conduct can count as acceptance of the counter-offer (Article 18(1) CISG). The acceptance takes effect when it reaches the other party or, where the offer, practices established between the parties or usage allow acceptance by performance without notice, when the act is performed (Article 18(2) and (3)). On this reading, the terms referred to last apply. That is the opposite of the Dutch first shot rule.

The practical objections against the last shot rule are substantial. Parties would endlessly continue referencing their own conditions to have the final word. Deliveries, invoices, and even payment reminders would become instruments in the battle for applicability. The knock out rule prevents this behaviour by rewarding neither party.

How do you protect your business in a dispute over general terms and conditions?

Enterprises protect themselves by providing conditions timely, documenting references, recording rejections in writing, and seeking legal advice before disputes escalate when uncertainty exists.

Documentation forms the foundation of every strong position in a battle of forms. Preserve all correspondence referencing conditions. Record when conditions were sent and received. Use systems that automatically include conditions with quotations and order confirmations. Digital timestamps and read receipts strengthen your evidentiary position considerably.

When it is unclear which terms apply, preventive action is usually wiser than litigation. Proceedings about general terms can be costly. Advice before the contract is concluded is usually cheaper than a dispute afterwards.

Contact our law firm in Amsterdam for personal legal advice about general terms and conditions in international commercial agreements. Our contract law specialists assess your conditions and advise on the optimal strategy for cross-border trade.

Frequently asked questions about the battle of forms under the Vienna Sales Convention

What is the knock-out rule under the Vienna Sales Convention?

Under the knock-out rule, a contract is concluded on the basis of the negotiated terms and those standard terms of both parties that are common in substance; conflicting terms drop out and the CISG or the applicable national law fills the gap. The CISG Advisory Council favours this rule (Opinion No. 13, Rule 10), but its opinions are not binding on courts.

Does the CISG apply the knock-out rule or the last shot rule?

The CISG has no specific battle-of-forms rule. A strict reading of Article 19 CISG leads to the last shot rule: a reply with materially different terms is a counter-offer, which the other party can accept by performing (Article 18 CISG). According to the CISG Advisory Council, most commentators and court decisions favour the knock-out rule. The outcome therefore remains uncertain.

How does the battle of forms under the CISG differ from Article 6:225(3) Dutch Civil Code?

Under Article 6:225(3) Dutch Civil Code, the second reference to general terms has no effect unless it expressly rejects the first terms; in principle, the first terms apply. That rule only applies if Dutch law governs and the CISG does not apply. Under the CISG, either the knock-out rule or the last shot rule applies.

When does the Vienna Sales Convention apply to international sales contracts?

It applies to sales of goods between parties whose places of business are in different contracting states, or where private international law leads to the law of a contracting state (Article 1(1) CISG). Consumer purchases are in principle excluded (Article 2(a)). Parties can exclude the CISG (Article 6); a choice of Dutch law alone generally does not do so. 97 states are party to the CISG (UNCITRAL, October 2026).

How do you make sure your own general terms apply under the CISG?

Agree in the main contract which set of terms applies, and send your terms to the other party before the contract is concluded. Terms first sent afterwards, for example with an invoice, are in principle not incorporated (CISG Advisory Council Opinion No. 13, Rule 4). If you do not accept the other party’s terms, say so clearly and in time (Rule 10).