Definition
To knock down property at auction is to finalize its sale to the highest bidder by the auctioneer's decisive signal — traditionally the fall of a hammer, but also by any other audible or visible announcement that communicates to the bidder that the lot is theirs upon payment of the bid price under the terms of the sale. The moment of knocking down marks the point at which a binding contract of sale is formed between seller and buyer at auction.
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Common Language
Modern common usage (Wiktionary): To knock down means generally to cause something to fall by striking it, or colloquially, to reduce a price through negotiation.
Historical common usage (Webster's 1913): To knock down is to fell or prostrate by a blow; also used in the context of auctions to mean assigning property to the highest bidder by a stroke of the hammer.
By 1913, the auction sense was already established in ordinary usage, which narrows the gap between common and legal meaning. The legal precision, however, lies in what the act accomplishes: it is not merely a procedural gesture but the operative event that concludes the contract. Common usage treats the knock as a formality; the law treats it as the moment of legal commitment.
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Common Confusion
"Knocked down" and "struck off" are synonymous in auction law and should be treated as interchangeable when encountered in historical sources. Researchers should not read any distinction of meaning between the two phrases; Black's 2nd Edition expressly equates them. Separately, the knock down should not be confused with the mere acceptance of a bid — at common law and in many statutory frameworks, the auctioneer retains discretion to refuse bids or withdraw the lot until the knock down occurs. The contract is not formed by the highest bid; it is formed by the knock down.
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Why It Matters in Research
The knock down is the pivotal moment in auction contract formation, and its precise legal significance has generated litigation over when, exactly, a seller becomes bound. Researchers working in real property, commercial sales, or creditors' rights will encounter knock down language in:
— Sale in execution and sheriff's sale records, where the moment of knock down determines priority and the validity of title transfer.
— Foreclosure sale disputes, where a bidder may claim contract rights based on the auctioneer's signal before a sale is halted or withdrawn.
— Goods sold under the Uniform Commercial Code (Article 2), which preserves the auctioneer's ability to withdraw lots before knock down, codifying the common law rule.
Historical sources before the mid-twentieth century will use "knocked down" and "struck off" interchangeably without explanation; do not treat the variation as legally meaningful. Sources may also describe knock down in non-hammer contexts — a nod, a verbal declaration, a gavel strike — and the same legal effect attaches regardless of the physical form of the signal.
Researchers in commercial real estate or construction will find that knock down rarely appears as a term of art in modern transactional drafting, but remains relevant in distressed asset sales, UCC Article 9 dispositions, and tax lien auction procedures.
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Historical Dictionary Support
Black's 2nd Edition (Supplemental) provides a clean and functionally complete definition: knock down occurs when the auctioneer, by hammer fall or any audible or visible announcement, signifies to the bidder entitlement to the property upon payment. The entry expressly equates "knocked down" with "struck off" and cites Sherwood v. [citation incomplete in source material].
The historical entry is adequate for basic identification of the term but does not address the contract-formation implications, the seller's right to withdraw before knock down, or the treatment of knock down in statutory sale frameworks. Researchers should supplement with treatise literature on auction law and, for goods, the UCC commentary on Article 2-328, which codifies and in some respects modifies the common law knock down rule.
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Jurisdictional Note
The fundamental rule — that contract formation at auction occurs at the moment of knock down — is consistent across common law jurisdictions. Statutory variations exist in foreclosure, tax sale, and execution sale procedures, where some states impose confirmation requirements that delay the legal effect of the knock down. Researchers should verify applicable state procedure before treating knock down as the conclusive moment of sale in judicial or quasi-judicial auction contexts.
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