UCC Section 2-207: Battle of the Forms and Knock-Out Rule

Under UCC Section 2-207, the battle of the forms is resolved by letting a contract form even when the buyer’s and seller’s paperwork don’t match, then using a separate set of rules to decide which clauses survive. The statute replaces the old requirement that an acceptance mirror the offer exactly, and it treats most responses that show intent to deal as valid acceptances. The harder question, almost always, is which fine-print terms end up binding the parties.¹

Why the Old Rule Had to Go

Before the UCC, courts applied the mirror image rule. An acceptance had to match the offer in every detail; if the seller’s acknowledgment added a single new clause, the law treated the response as a rejection and a counter-offer. The buyer then had to accept the counter-offer, and in practice, whoever sent the last form before shipment or payment began won, because the other side’s performance was deemed acceptance of that final form. This was the “last shot” doctrine, and it rewarded whoever managed to get the final piece of paper in.

Section 2-207 scraps that approach. A response that shows a clear intent to accept creates a contract even if it adds or changes terms.¹ If a buyer sends a purchase order for 500 widgets at $10 each and the seller returns an acknowledgment that tacks on a limitation-of-liability clause, a contract exists. What remains is deciding whether that new clause is part of it.

When Section 2-207 Applies

Section 2-207 sits inside Article 2 of the UCC, which only governs the sale of goods. Transactions in land, employment, or pure services fall outside it, and common-law contract principles (including the mirror image rule) still control there.

Many deals mix the two. Courts apply the “predominant purpose test” to hybrids like custom software bundled with installation and training: if the primary thing bargained for was a product, Article 2 covers the whole transaction; if it was the service, Article 2 does not. Contract language, the nature of the supplier’s business, and the cost breakdown all factor in.

Software adds its own wrinkle. Courts have generally treated off-the-shelf software sold in a one-time deal as a good under the UCC, especially when the arrangement looks like a traditional sale with a single payment and permanent access. Ongoing licenses with recurring payments and no transfer of ownership are less likely to qualify. A proposed uniform law called UCITA aimed to handle software directly, but only two states adopted it, so courts continue analyzing software deals case by case under existing UCC principles.

Whether Added Terms Become Part of the Deal

When an acceptance adds terms the offer didn’t contain, Section 2-207(2) decides whether those terms stick. The answer turns on who the parties are.¹

If Either Party Is Not a Merchant

Additional terms are treated as mere proposals. They do not become part of the contract unless the offeror expressly agrees to them.¹ Consumers and occasional buyers can’t get locked into clauses buried in a seller’s form.

Between Merchants

A merchant is someone who regularly deals in the type of goods involved or holds themselves out as having specialized knowledge of the trade.² Between two merchants, added terms automatically join the contract unless one of three things is true:

The offer expressly limited acceptance to its own terms. Language in the purchase order like “this order is limited to the terms stated here” blocks new clauses from entering.
The added term materially alters the contract.
The offeror objects within a reasonable time, or has already objected.¹

The default rule for merchants reflects an assumption that professionals know what’s in the forms they send and receive. The material alteration exception is where that assumption gets tested.

What Counts as a Material Alteration

Between merchants, the most common ground for excluding an added term is that it materially alters the deal. The test is whether including the term without the other party’s knowledge would cause unreasonable surprise or hardship.¹

The official comments to Section 2-207 list examples. Clauses that typically qualify as material alterations include provisions eliminating standard implied warranties (such as merchantability or fitness for a particular purpose), requirements that disputes be arbitrated in a distant location, and terms letting a seller cancel if the buyer misses a single payment. Each dramatically shifts risk from what a reasonable merchant would expect based on the original offer.

The comments also identify terms minor enough to join a merchant contract without express agreement: reasonable deadlines for filing complaints, commercially standard credit terms, and remedy limits consistent with normal trade practices. If a clause reflects what most contracts in the industry already include, it’s unlikely to cause surprise.

Indemnification and attorney fees sit in a genuine gray area. Some courts treat indemnification clauses as material alterations per se, others find them reasonable as a matter of law, and a third group evaluates them case by case based on prior dealings, industry custom, and whether the clause was conspicuous. Attorney fees provisions get similarly inconsistent treatment. If your form adds either, assume the other side will challenge it.

Additional Terms Versus Different Terms

Section 2-207’s first subsection mentions both “additional” and “different” terms, but subsection (2), which spells out how extra terms get handled, only addresses “additional” terms. That silence has produced a three-way split, and the approach your jurisdiction follows can decide the dispute.

The distinction itself is straightforward. An additional term adds something the offer didn’t address, like an arbitration clause in a response to an offer silent on dispute resolution. A different term contradicts something the offer already said, like the buyer’s form specifying a two-year warranty while the seller’s form limits warranties to 90 days.

Courts have taken three approaches to different terms:

The knock-out rule. The conflicting provisions from both forms cancel out, and UCC gap-filler provisions replace them. Most courts follow this approach and find support for it in the official commentary to Section 2-207.
Treating different terms like additional terms. The same Section 2-207(2) analysis applies, so between merchants a different term can enter the contract unless it materially alters the deal, the offer limited acceptance, or the offeror objected.
The offeror’s terms prevail. A minority of courts reason that because 2-207(2) doesn’t mention different terms, nothing lets them into the contract, and the offeror’s original language controls.

The practical takeaway is that if your form contradicts the other side’s on something that matters, the outcome depends heavily on which court will hear the dispute. Negotiating those provisions directly, rather than relying on form language, removes the uncertainty.

How Courts Apply the Knock-Out Rule

When the knock-out approach controls, the directly conflicting provisions from both sides come out of the contract entirely. Neither version survives.³ The gaps get filled by the UCC’s default provisions.

In Daitom, Inc. v. Pennwalt Corp., the Third Circuit endorsed this approach and reasoned that it prevents either party from gaining an advantage based on the timing of its paperwork. The court noted that even when a knocked-out clause gets replaced by a UCC gap-filler resembling one party’s original term, the result is still fair because the gap-filler reflects a balance the UCC’s drafters built in.³

The alternatives have obvious drawbacks. The last-shot rule rewards whoever gets the final form in and encourages endless rounds of counter-forms. Letting the offeror always win creates the opposite arbitrary result. The knock-out rule treats the parties as having agreed only on what they actually agreed on.

The “Expressly Conditional” Escape Hatch

Section 2-207(1) contains an important carve-out. If the acceptance is “expressly made conditional on assent to the additional or different terms,” it isn’t an acceptance at all. It functions as a counter-offer the way the old mirror image rule would have treated it.¹

Courts read this proviso narrowly. Boilerplate stating that a response is “subject to” the terms on the back of the form has been held insufficient. In Dorton v. Collins & Aikman Corp., the court found that “subject to” language didn’t expressly condition acceptance on the buyer’s assent. To trigger the proviso, the acceptance has to clearly communicate that no deal exists unless the other side agrees to the new or changed terms.

Using this proviso is risky by design. A seller that drafts aggressive conditional language prevents the writings from forming a contract. If both parties then ship and pay anyway, they fall into Section 2-207(3), where the contract gets stripped down to overlapping terms plus UCC defaults. The aggressive provisions the seller was trying to impose get stripped out entirely, often leaving the seller in a worse position than if it had simply accepted the buyer’s offer and relied on the material alteration doctrine.

When Performance Creates the Contract

Sometimes the writings fail to form a contract, but the parties behave as if one exists anyway. The seller ships, the buyer accepts and pays, and nobody raises the paperwork problem until a dispute surfaces months later. Section 2-207(3) handles this: when both parties’ conduct recognizes a contract, a contract exists even though the writings didn’t produce one.¹

This routinely happens after a seller invokes the expressly-conditional proviso, the buyer never assents, and both sides perform anyway. The proviso prevented the writings from creating a contract, but the shipping and paying create one under subsection (3).

The catch is a narrow set of terms. A conduct-based contract includes only the provisions both forms agreed on, plus UCC gap-fillers.¹ One-sided provisions each party tried to insert through its own form drop out.

The Gap-Fillers That Step In

When conflicting terms get knocked out or a contract forms through conduct, the UCC supplies defaults for the missing pieces. A few of the most common:

Price. If the contract doesn’t settle one, the buyer owes a reasonable price at the time of delivery. If one party is supposed to set it, they must do so in good faith. If both sides intended not to be bound without an agreed price and they never reached one, there’s no contract.⁴
Place of delivery. Delivery happens at the seller’s place of business unless the parties agreed otherwise. If the goods are elsewhere and both sides know it, delivery is at that location.⁵
Payment timing. Payment is due when the buyer receives the goods. If the seller ships on credit, the credit period runs from the date of shipment.⁶

These defaults are deliberately unremarkable, reflecting what reasonable commercial parties would probably agree to if they negotiated the point. When forms fail, the UCC provides a sensible backstop instead of letting the transaction fall apart.

How to Protect Your Terms

Knowing how Section 2-207 operates matters only if it changes how you handle your paperwork. A few steps prevent the common problems.

If you’re the offeror and you don’t want added terms sliding in, include a clear limitation in your purchase order. Language like “acceptance is limited to the terms stated in this order, and any additional or different terms are objected to” invokes Section 2-207(2)(a) and blocks new clauses between merchants.¹ Keep it conspicuous rather than buried on the back in small type.

If a term genuinely matters, negotiate it directly instead of trusting boilerplate. Warranty limitations, indemnification obligations, and dispute resolution clauses are exactly the provisions that get knocked out, excluded as material alterations, or stripped away in a conduct-based contract. A separately signed agreement on those points takes them out of the battle of the forms.

Review incoming forms promptly and object in writing to anything you don’t accept. Under Section 2-207(2)(c), a timely objection prevents added terms from entering a merchant-to-merchant contract.¹ Letting forms sit unopened is how companies end up bound by terms they never meant to accept.

Finally, treat the expressly-conditional proviso as a high-risk strategy. Courts read the language strictly, most boilerplate falls short, and even when the proviso does its job, the resulting contract (formed by performance) usually contains only overlapping terms and UCC defaults. In many cases, that outcome is worse than simply accepting the other side’s offer and relying on the material alteration doctrine to cut out the worst provisions.

1
Cornell Law Institute. Uniform Commercial Code 2-207 – Additional Terms in Acceptance or Confirmation
2
Legal Information Institute. UCC 2-104 – Definitions: Merchant, Between Merchants, Financing Agency
3
Justia Law. Daitom Inc v Pennwalt Corporation
4
Legal Information Institute. UCC 2-305 – Open Price Term
5
Legal Information Institute. UCC 2-308 – Absence of Specified Place for Delivery
6
Legal Information Institute. UCC 2-310 – Open Time for Payment or Running of Credit