Definition
A Latin verbal form used in old English law meaning "I warrant." The term appears in medieval legal instruments and pleading records as the first-person singular declaration by which a grantor or feoffor formally undertook to warrant — that is, to guarantee and defend — the title conveyed to a grantee. Its noun cognate, WARANTUS (also rendered Warrantus), designated the individual who had made such a covenant of warranty and who could therefore be called into a proceeding to defend the grantee's seisin against a claimant asserting a superior title.
The practical operation of warantizo was as follows: if a grantee holding land under a deed containing the warrantor's covenant were challenged by a third party claiming title, the grantee could "vouch to warranty" — formally call upon — the warrantor to enter the action and defend. If the warrantor failed to defend successfully and the grantee lost the land, the warrantor was obliged to yield equivalent land in exchange. The single word warantizo thus carried, in written instruments, the full weight of this obligation.
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Common Confusion
WARANTIZO, WARANTUS, and WARRANTY are related but distinct. Warantizo is the verbal act — the first-person declaration of warranting. Warantus is the person who made that declaration and bore the consequent obligation. WARRANTY, in its modern form, is the covenant or contractual promise abstracted from the feudal pleading context. Researchers encountering warantizo in a medieval charter or Fleta should not read it as a synonym for modern contractual warranty without accounting for the procedural mechanism — voucher to warranty — that gave it practical effect in real actions.
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Why It Matters in Research
This is a term of very narrow historical range. Researchers will encounter warantizo almost exclusively in three contexts: transcriptions or analyses of medieval English charters and conveyancing instruments; treatises on the old real actions, particularly the writ of right and its variants; and discussions of voucher to warranty in works such as Fleta, Bracton, and Littleton's Tenures.
The key navigational point is that warantizo is a formula word embedded in feudal conveyancing, not a standalone doctrine. Its meaning cannot be separated from the procedural machinery of voucher to warranty. A researcher who finds the term in a primary source but looks only to modern warranty doctrine for interpretive context will miss the real-action pleading structure entirely.
Within the Law Mind corpus, warantizo is most likely to surface as a bridge term: it connects charter language to real-action procedure, which in turn connects to the feudal theory of tenure and seisin. Tracing it outward leads quickly to VOUCHER TO WARRANTY, WARRANTIA CHARTAE (the specific writ available when voucher was unavailable), and ultimately to the decline of the real actions after the English reforms of the nineteenth century. American law never adopted the real actions with their feudal machinery, so warantizo as a live term has no American legal history — but it appears in American treatises on title and conveyancing history that trace warranty covenants back to their English roots.
Researchers using historical dictionaries should note that entries for warantizo and warantus are often compressed, with Burrill providing the core reference to Fleta but not elaborating the procedural context. The fuller treatment of the underlying institution is in Fleta itself (Book 5) and in Bracton's De Legibus et Consuetudinibus Angliae.
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Historical Dictionary Support
Burrill's Law Dictionary provides the essential entry: warantizo translates as "I warrant" and is cited to Fleta, lib. 5, c. 4, § 4. Burrill's companion entry for warantus supplies the relational definition — the warrantor as someone who "had covenanted to warrant another's title" and who "might, therefore, be called upon, or vouched to warrant and defend it." The partial quotation from Fleta that Burrill includes — "Habet forte tenens warantum et defensorem, qui eum defendere tenetur in seysina sua contra petentem" ("the tenant perhaps has a warrantor and defender, who is bound to defend him in his seisin against the demandant") — captures the procedural stakes precisely: the warrantor's obligation ran to the defense of the grantee's actual possession (seisin), not merely to abstract title.
What historical dictionaries including Burrill tend to omit is any account of what happened when the warranty failed — the exchange of equivalent land — which is the mechanism that made the covenant economically significant rather than merely formal. For that dimension, researchers must go to Bracton or to later English treatises on real property.
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Jurisdictional Note
Warantizo is a term of English medieval law with no independent life in American jurisdictions. American conveyancing adopted the covenant of warranty as a deed covenant, but stripped of the real-action procedural framework, the term itself did not travel. It appears in American legal history and title-chain scholarship only when tracing the origins of warranty covenants in English practice.
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