Battle of forms

Battle of the forms (서식의 싸움, 약관의 충돌) takes place when the content of standard form contained in an offer or acceptance conflicts each other while making a contract.

It is usually illustrated by a situation like this:

When two companies deal with each other in the course of business, they will use standard form contracts. Often these terms conflict (e.g. both parties include a liability waiver in their form) and yet offer and acceptance are achieved forming a binding contract. The battle of the forms refers to the resulting legal dispute of these circumstances, wherein both parties recognize that an enforceable contract exists, however they are divided as to whose terms govern that contract. Under English law, the question was raised in Butler Machine Tool Co Ltd v. Ex-Cell-O Corporation (England) Ltd [1979] WLR 401, as to which of the standard form contracts prevailed in the transaction. Lord Denning MR preferred the view that the documents were to be considered as a whole, and the important factor was finding the decisive document; on the other hand, Lawton and Bridge LJJ preferred traditional offer-acceptance analysis, and considered that the last counter-offer prior to the beginning of performance voided all preceding offers. The absence of any additional counter-offer or refusal by the other party is understood as an implied acceptance. In U.S. law, this principle is referred to as the "last shot rule".

Key words
offer, acceptance, contract, standard form, last shot doctrine, knock-out principle

Korean law
The Civil Act and the Commercial Act of Korea have no provisions concerning the battle of forms. In such a case, Article 534 of the Civil Act may be invoked. In other words, is the Civil Act consistent with the "mirror image rule"? No, it is not always so. It depends on whether the contract is materially changed or not subject to the interpretation of the intent of the relevant party concerning the conditions or modifications of the contract.

Uniform Commercial Code
Previously, under the Uniform Commercial Code (UCC) Sec. 2-207(1), a definite expression of acceptance or a written confirmation of an informal agreement may constitute a valid acceptance even if it states terms additional to or different from the offer or informal agreement. The additional or different terms are treated as proposals for addition into the contract under UCC Sec. 2-207(2). Between merchants, such terms become part of the contract unless:
 * a) the offer expressly limits acceptance to the terms of the offer,
 * b) material alteration of the contract results,
 * c) notification of objection to the additional/different terms are given in a reasonable time after notice of them is received.

Material is defined as anything that may cause undue hardship/surprise, or is a significant element of the contract. If there is no contract under UCC Sec. 2-207(1), then under UCC Sec. 2-207(3), conduct by the parties that recognize there is a contract may be sufficient to establish a contract. The terms for this contract include only those that the parties agree on and the rest via gap fillers. Under the newly amended Articles 2-206(3) and 2-207, the following things are to be added:
 * Formation of a contract: Article 2-206(3)
 * Established contractual conditions: Article 2-207

UN Sales Convention
United Nations Convention on Contracts for the International Sale of Goods (CISG, UN Sales Convention) has no provisions about "battle of the forms". In this context, Article 19 has a significant meaning for interpretation.

Accordingly, when there is no substantial differece between the forms of both parties, the contract is deemed to be formed on the basis of the offeree's form unless the offeror, without undue delay, objects orally to the discrepancy or dispatches a notice to that effect.

On the contrary, if there is a substantial difference, there must be a new counter-offer. Insofar as the offeror does not accept it, the contract fails to be formed. However, if the offeror impliedly accepts it by implementing the contract, then the offeree's form turns out to prevail. It is referred to the "last shot doctrine".

Alternatively, someone calls on the "knock-out principle", which acknowledges only the consistent part of the conflicting forms, and causes a contract to be formed to that extent. In Germany, the court as well as a majority of scholars follow this principle.

In conclusion, even though there are difference and discrepancy in the forms of both parties, a contract seems to be formed to the extent that both parties have entered into the contract excluding such difference and discrepancy in line with implied agreement, customs and practice.