Glossary
Battle of the forms
A battle of the formsA battle of the forms happens when each side says the deal is on its own standard terms. English law looks for which offer was accepted, often the last shot before performance. Butler Machine Tool Co Ltd v Ex-Cell-O Corp [1979] 1 WLR 401 is the leading case. A signed master that beats later POs is the clean fix.More in the glossary happens when each side says the deal is on its own standard terms. English law looks for which offer was accepted, often the last shot before performance. Butler Machine Tool Co Ltd v Ex-Cell-O Corp [1979] 1 WLR 401 is the leading case. A signed master that beats later purchase orderA purchase order is a buyer's written request to buy named goods or services on stated terms. It can form a contract if it is an offer that the supplier accepts. When each side fires its own standard terms, you have a battle of the forms. A master services agreement should say that its terms beat any PO small print.More in the glossary is the clean fix.
Last updated 28 October 2026
The classic facts: a quote on seller terms, a purchase order on buyer terms, an acknowledgement, then delivery. Each paper says “our terms apply.” Lord Denning in Butler described the last shot, the first shot, and the synthesis approaches; the majority treated it as ordinary offer and acceptance. The last document before performance often wins if the other side then performs.
We do not want you in that fight. A signed master services agreement or statement of work with an order-of-precedence line beats later PO small print. Lex puts that line at the top. Quote the PO number for the client’s accounts; do not sign the PO’s own terms.
Whose terms win?
The terms that were accepted. That is often the last form sent before the work started, if the other side then performed without objection. It can also be an earlier form if the later paper was only an accounts note. There is no mechanical “last shot always wins” rule. The facts of acceptance decide it.
How do we avoid a battle?
Sign one contract first. Write that it prevails over any PO, release or portal tick. Do not acknowledge a PO “on your terms attached.” If you must use a PO number, say it is for reference only. See purchase order and entire agreement clause.
Does a last shot always win?
No. Butler is read as offer and acceptanceOffer and acceptance is how a bargain is formed in England and Wales: one side makes a clear offer and the other accepts the same terms. A counter-offer kills the original offer. A price list or advert is usually only an invitation to treat. Carlill v Carbolic Smoke Ball Co [1893] 1 QB 256 is the classic case.More in the glossary, not as a special last-shot doctrine. If the buyer’s PO was an offer on buyer terms and the seller delivered without a further seller-terms acknowledgement, the buyer’s terms may win. If the seller’s acknowledgement was a counter-offer and the buyer took delivery, the seller’s terms may win.
What if both sets of terms are silent on a point?
The gap is filled by implied termsImplied terms are obligations the law reads into a contract even when the parties did not write them down. In England and Wales they come from statute — for business services, reasonable care and skill under the Supply of Goods and Services Act 1982 s.13 — or from common law where a term is necessary for business efficacy.More in the glossary and the statute — for goods, the Sale of Goods Act 1979; for services, the Supply of Goods and Services Act 1982 s.13 (reasonable care and skill). That is a poor substitute for a liability cap you actually agreed.
A worked example
A studio quotes on its one-page terms, cap at the fee. The client sends a PO on buyer terms, unlimited liability, Net 60. The studio does not acknowledge those terms. It sends a shared MSA that says it prevails over any PO, both sides e-sign, and then it starts. There is no battle. If it had started on the PO alone, Butler would have something to chew on.
How it shows up in a contract
Sample wording · our own drafting
This agreement is the entire contract for the Services. It prevails over any purchase order, acknowledgement, portal terms or other standard terms, whether earlier or later. Performance is not acceptance of any other form. A purchase-order number is for the Client's reference only.
In Plain English
This signed paper is the deal. It beats any PO or portal terms, before or after. Doing the work is not a yes to someone else’s small print. The PO number is only for the client’s accounts.
Common mistakes
- Starting work after a PO “on our terms attached” and hoping your quote still governs.
- Sending a seller acknowledgement and a buyer PO and never signing a master.
- Ticking a vendor portal after you already have a signed cap.
- Assuming “last shot always wins” without looking at what was actually accepted.
Frequently asked questions
What is the battle of the forms?
The fight that happens when each side says the deal is on its own standard terms. English law treats it as offer and acceptance. Butler Machine Tool [1979] 1 WLR 401 is the case.
Whose terms win?
The terms that were accepted. That is often the last form before performance, but not as a mechanical rule. The facts decide it.
How do we avoid a battle?
Sign one contract that says it prevails over any PO. Quote the PO number for accounts only. See /glossary/purchase-order.
Does a last shot always win?
No. Butler is ordinary offer and acceptance, not a special last-shot doctrine. Look at which paper was accepted.
Related
The legal wording governsLast reviewed 28 October 2026Pending lawyer review