UCC 2-207 and the Battle of the Forms

Under the common law mirror image rule, an acceptance must match the offer exactly; any variation is a counteroffer rather than an acceptance. That rule produced a specific commercial pathology known as the last shot doctrine.

The pathology worked like this. A buyer sends a purchase order with its standard terms. The seller responds with an acknowledgment containing its own boilerplate, which differs. Under mirror image, the acknowledgment is a counteroffer. Neither side reads the other's fine print, the goods ship, the buyer accepts them, and that acceptance-by-performance is treated as accepting the counteroffer. The party who sent the last form before performance wins on every disputed term — not because the parties agreed, but because of the order in which paperwork moved.

UCC 2-207 rejects that result for the sale of goods. Its central move is to separate the question of whether a contract exists from the question of what terms it contains. Under the common law those questions had a single answer; under 2-207 they are analyzed independently, and that separation is the key to the section.

A definite and seasonable expression of acceptance, or a written confirmation sent within a reasonable time, operates as an acceptance even though it states terms additional to or different from those offered — unless acceptance is expressly made conditional on assent to the additional or different terms.

Two elements do the work. First, the response must be a definite expression of acceptance: it must indicate the responding party intends to close a deal, rather than to negotiate. A response that alters price, quantity, or the subject matter itself is generally not a definite expression of acceptance and falls outside 2-207(1) entirely.

Second, the proviso. A response is a counteroffer rather than an acceptance only if it is expressly conditional on the other party's assent to the new terms. Courts read this narrowly and require language tracking the statute closely — an unambiguous statement that the responding party is unwilling to proceed unless the offeror agrees to the new terms. Boilerplate reciting that the response is "subject to the terms and conditions herein" ordinarily does not qualify.

If the proviso is satisfied, no contract forms on the exchange of documents. If the parties then perform anyway, subsection (3) governs.

Additional terms are construed as proposals for addition to the contract. If either party is not a merchant, the additional terms are mere proposals and do not become part of the contract unless the offeror expressly agrees to them.

Between merchants, additional terms become part of the contract automatically unless one of three conditions applies: the offer expressly limits acceptance to its own terms; the term materially alters the contract; or notification of objection has already been given or is given within a reasonable time after notice of the term is received.

Material alteration is the contested element and the one worth developing on an exam. The official commentary frames it as whether the term would result in surprise or hardship if incorporated without express awareness. Terms commonly held to materially alter include disclaimers of implied warranties, clauses requiring the buyer to bring complaints within an unreasonably short period, and provisions imposing substantial penalties or one-sided remedy limitations. Terms commonly held not to alter materially include ordinary provisions for interest on overdue invoices and clauses fixing reasonable limits on the seller's liability for defects within customary trade practice.

Whether an arbitration clause materially alters is genuinely contested and varies by jurisdiction and by industry practice — a good place to note the split rather than assert an answer.

Subsection (2) by its text addresses additional terms. Terms in the response that directly contradict terms in the offer are different terms, and the statute's treatment of them is famously incomplete. Three approaches exist.

The majority approach is the knockout rule: conflicting terms cancel each other out, and the resulting gap is filled by the UCC's default provisions — the implied warranties, the standard remedies, the gap-filling rules on price, delivery, and time. Comment 6 to 2-207 supports this reading, and it is the approach most courts follow. Its rationale is symmetry: neither party assented to the other's clause, so neither should prevail by accident of drafting.

A minority approach treats different terms as governed by subsection (2) alongside additional terms, meaning a non-materially-altering different term could enter the contract between merchants. A second minority approach holds that different terms simply drop out and the offeror's terms control, on the reasoning that the offeror should not lose ground by the other party's variation.

The practical consequence of the knockout rule is that gap-filling defaults frequently supply the operative term. If the seller's form disclaims implied warranties and the buyer's form expressly preserves them, the clauses knock out and the Code's implied warranty of merchantability applies — which is to say the buyer wins, but through the default rather than through its own form.

Where the writings do not establish a contract but the parties' conduct recognizes the existence of one, subsection (3) supplies a contract. This is the provision that applies when a response was expressly conditional under the (1) proviso, or when the forms diverge so sharply that no acceptance occurred, and the parties nonetheless shipped, paid, and performed.

The terms are those on which the writings agree, together with any supplementary terms incorporated under other provisions of the Code. Every term appearing in only one form drops out, regardless of whether it was additional or different, material or immaterial.

This is the most decisive route in practice, because a party relying on a term unique to its own form loses that term entirely. The leading illustration is Northrop Corp. v. Litronic Industries, though courts diverge on the surrounding analysis. The operational point is that subsection (3) is more hostile to boilerplate than subsection (2) — which is why identifying whether the case runs through (2) or (3) usually determines the outcome.

Applying 2-207 outside its scope. Article 2 governs transactions in goods. Contracts for services, real property, or intangibles are governed by the common law mirror image rule, and mixed contracts require a predominant purpose analysis before the section applies at all.

Skipping the merchant determination. Subsection (2)'s automatic-inclusion rule operates only between merchants. Where one party is a consumer, additional terms are proposals and almost never enter the contract, which shortens the analysis considerably.

Treating any boilerplate reservation as satisfying the expressly-conditional proviso. Courts require language closely tracking the statute and expressing genuine unwillingness to proceed without assent. Getting this wrong routes the entire problem through the wrong subsection.

Conflating additional and different terms. Additional terms supplement; different terms contradict. They receive different treatment, and identifying which category a clause falls into should come before analyzing material alteration.

Concluding that the knockout rule leaves a gap. It leaves a gap in the parties' writings, which the Code's default provisions then fill. The contract is not silent on the point — it is governed by the default.