United Nations Convention on Contracts for the International Sale of Goods

The United Nations Convention on Contracts for the International Sale of Goods, sometimes known as the Vienna Convention, is a multilateral treaty that establishes a uniform framework for international commerce. As of September 2023, it has been ratified or acceded to by 97 countries, representing two-thirds of world trade.
The CISG facilitates international trade by removing legal barriers among state parties and providing uniform rules that govern most aspects of a commercial transaction, such as contract formation, the means of delivery, parties' obligations, and remedies for breach of contract. Unless expressly excluded by the contract, the convention is automatically incorporated into the domestic laws of Contracting States and applies directly to a transaction of goods between their nationals.
The CISG is rooted in two earlier international sales treaties first developed in 1930 by the International Institute for the Unification of Private Law. When neither convention garnered widespread global support, the United Nations Commission on International Trade Law drew from the existing texts to develop the CISG in 1968. A draft document was submitted to the Conference on the International Sale of Goods held in Vienna, Austria in 1980. Following weeks of negotiation and modification, the CISG was unanimously approved and opened for ratification; it came into force on 1 January 1988 following ratification by 11 countries.
The CISG is considered one of the greatest achievements of UNCITRAL and the "most successful international document" in unified international sales law, due to its parties representing "every geographical region, every stage of economic development and every major legal, social and economic system". Of the uniform law conventions, the CISG has been described as having "the greatest influence on the law of worldwide trans-border commerce", including among nonmembers. It is also the basis of the annual Willem C. Vis International Commercial Arbitration Moot, one of the largest and most prominent international moot court competitions in the world.
CISG art. 66 is a supplement to an inadequate Incoterms rule; CISG also coworks with Rome I and UCP 600 for standardization of the rules governing Letters of Credit to standardise transactions and benefit all parties and the maritime law about liability of the carrier.

Adoption

As of 1 September 2025, the following 97 states have ratified, acceded to, or succeeded to the convention:
The convention has been signed, but not ratified, by Ghana and Venezuela.
The former Yugoslavia had signed and ratified the Convention on 11 April 1980 and 27 March 1985, respectively. Bosnia and Herzegovina, Croatia, Slovenia and North Macedonia became parties by succession.
Czechoslovakia had signed and ratified the Convention on 1 September 1981 and 5 March 1990, respectively. The Czech Republic and Slovakia became parties by succession.

Language, structure, and content

The CISG is written using "plain language that refers to things and events for which there are words of common content". This was intended to allow national legal systems to be transcended through the use of a lingua franca that would be mutually intelligible among different cultural, legal, and linguistic groups. and to avoid "words associated with specific domestic legal nuances". As is customary in UN conventions, all six official languages of the UN are equally authentic.
The CISG is divided into four parts:

Part I: Sphere of Application and General Provisions (Articles 1–13)

The CISG applies to contracts of the sale of goods between parties whose places of business are in different States, when the States are Contracting States ). Given the significant number of Contracting States, this is the usual path to the CISG's applicability.
The CISG also applies if the parties are situated in different countries and the conflict of law rules lead to the application of the law of a Contracting State. For example, a contract between a Japanese trader and a Brazilian trader may contain a clause that arbitration will be in Sydney under Australian law with the consequence that the CISG would apply. A number of States have declared they will not be bound by this condition.
The CISG is intended to apply to commercial goods and products only. With some limited exceptions, it does not apply to personal, family, or household goods, nor does it apply to auctions, ships, aircraft, or intangibles and services. The position of computer software is 'controversial' and will depend upon various conditions and situations.
Importantly, parties to a contract may exclude or vary the application of the CISG.
Interpretation of the CISG must consider the "international character" of the convention, the need for uniform application, and the need for good faith in international trade.
A key point of controversy is whether or not a contract requires a written memorial to be binding. The CISG allows for a sale to be oral or unsigned, but in some countries, contracts are not valid unless written. In many nations, however, oral contracts are accepted, and those States had no objection to signing, so States with a strict written requirement exercised their ability to exclude those articles relating to oral contracts, enabling them to sign as well.
The CISG, by its own definition, does not govern all aspects of sales contracts subject to its application. The matters listed in its Article 4 must be filled in by the applicable national law under due consideration of the conflict of law rules applicable at the place of jurisdiction. Gaps referring to matters that are governed by the CISG but not expressly settled therein, however, are to be preferably filled in accordance with "the principles on which is based," and only in the absence of those should national law be applied.

Part II: Formation of the Contract (Articles 14–24)

An offer to contract must be addressed to a person, be sufficiently definite – that is, describe the goods, quantity, and price – and indicate an intention for the offeror to be bound on acceptance. The CISG does not appear to recognise common law unilateral contracts but, subject to clear indication by the offeror, treats any proposal not addressed to a specific person as only an invitation to make an offer. Further, where there is no explicit price or procedure to implicitly determine price, then the parties are assumed to have agreed upon a price based upon that 'generally charged at the time of the conclusion of the contract for such goods sold under comparable circumstances'.
Generally, an offer may be revoked provided the withdrawal reaches the offeree before or at the same time as the offer, or before the offeree has sent an acceptance. Some offers may not be revoked; for example when the offeree reasonably relied upon the offer as being irrevocable. The CISG requires a positive act to indicate acceptance; silence or inactivity are not an acceptance.
The CISG attempts to resolve the common situation where an offeree's reply to an offer accepts the original offer, but attempts to change the conditions. The CISG says that any change to the original conditions is a rejection of the offer—it is a counter-offer—unless the modified terms do not materially alter the terms of the offer. Changes to price, payment, quality, quantity, delivery, liability of the parties, and arbitration conditions may all materially alter the terms of the offer.

Part III: Sale of Goods (Articles 25–88)

Articles 25–88; sale of goods, obligations of the seller, obligations of the buyer, passing of risk, obligations common to both buyer and seller.
The CISG defines the duty of the seller, 'stating the obvious', as the seller must deliver the goods, hand over any documents relating to them, and transfer the property in the goods, as required by the contract. Similarly, the duty of the buyer is to take all steps 'which could reasonably be expected' to take delivery of the goods, and to pay for them.
Generally, the goods must be of the quality, quantity, and description required by the contract, be suitably packaged and fit for purpose. The seller is obliged to deliver goods that are not subject to claims from a third party for infringement of industrial or intellectual property rights in the State where the goods are to be sold. The buyer is obliged to promptly examine the goods and, subject to some qualifications, must advise the seller of any lack of conformity within 'a reasonable time' and no later than within two years of receipt.
The CISG describes when the risk passes from the seller to the buyer but it has been observed that in practice most contracts define the seller's delivery obligations quite precisely by adopting an established shipment term, such as FOB and CIF.
Remedies of the buyer and seller depend upon the character of a breach of the contract. If the breach is fundamental, then the other party is substantially deprived of what it expected to receive under the contract. Provided that an objective test shows that the breach could not have been foreseen, then the contract may be avoided and the aggrieved party may claim damages. Where part performance of a contract has occurred, then the performing party may recover any payment made or good supplied; this contrasts with the common law where there is generally no right to recover a good supplied unless title has been retained or damages are inadequate, only a right to claim the value of the good.
If the breach is not fundamental, then the contract is not avoided and remedies may be sought including claiming damages, specific performance, and adjustment of price. Damages that may be awarded conform to the common law rules in Hadley v Baxendale but it has been argued the test of foreseeability is substantially broader and consequently more generous to the aggrieved party.
The CISG excuses a party from liability to a claim of damages where a failure to perform is attributable to an impediment beyond the party's, or a third party sub-contractor's, control that could not have been reasonably expected. Such an extraneous event might elsewhere be referred to as force majeure, and frustration of the contract.
Where a seller has to refund the price paid, then the seller must also pay interest to the buyer from the date of payment. It has been said the interest rate is based on rates current in the seller's State 'ince the obligation to pay interest partakes of the seller's obligation to make restitution and not of the buyer's right to claim damages', though this has been debated. In a mirror of the seller's obligations, where a buyer has to return goods the buyer is accountable for any benefits received.