Definition
A written instrument is any document that memorializes a legal act, obligation, right, or fact in written form and is intended to have legal effect. The term functions as a broad category, encompassing contracts, deeds, wills, promissory notes, bonds, leases, and other documents that record enforceable legal relationships or transactions.
The term most commonly appears in two research contexts:
1. Evidence and pleading rules. Statutes and procedural rules frequently require that written instruments be attached to or filed with pleadings when a claim is founded upon them. In this context, the definition becomes consequential: courts have had to determine what qualifies as a "written instrument" for purposes of these requirements.
2. Criminal law. Many jurisdictions define forgery and related offenses by reference to "written instruments," making the scope of the term central to the elements of the offense.
Common Confusion
The term sounds self-defining — any instrument that is written — but courts and legislatures have treated it as a term of art with a narrower reach than the plain language suggests. Not every writing qualifies. Judicial records such as judgments, and administrative documents such as tax duplicates, have been held to fall outside the definition of "written instrument" in pleading contexts, even though they are plainly writings and plainly have legal significance. The distinction generally turns on whether the document was created by private parties to establish a legal relationship, as opposed to being issued by a court or government authority as a record of a legal proceeding or official act. Researchers who assume that any legally significant writing is a "written instrument" within a given statute will miss this distinction.
Why It Matters in Research
The phrase "written instrument" carries different operative meaning depending on the statutory or procedural context in which it appears, and researchers must resist treating it as uniform across sources.
In pleading and procedure contexts, the key question is whether the document at issue was created to establish a private legal right or obligation. Bouvier's flags two instructive examples — judgments and tax duplicates held not to be written instruments for purposes of a pleading statute requiring copies to be filed. This is a trap: a researcher advising on whether a document must be attached to a complaint, or analyzing whether a forgery indictment is properly grounded, needs to locate how the relevant jurisdiction defines the term in that specific statutory context, not assume a universal definition.
In criminal law contexts, particularly forgery statutes, the definition of "written instrument" is often codified and may be expansive, sometimes explicitly including public records, official documents, and electronic records — reversing the narrower common law intuition. Modern state forgery statutes frequently contain their own definitional sections, and these definitions should be consulted directly rather than importing the narrower civil/pleading conception.
Historical sources are thin here. Bouvier's entry is brief and context-specific. Researchers working in historical corpora should treat any appearance of "written instrument" as an invitation to look at the surrounding statutory scheme rather than relying on dictionary authority alone.
Cross-corpus note: In the commercial law context, the concept of a written instrument intersects with the requirements for negotiability under UCC Article 3. A negotiable instrument is a subset of written instruments, but Article 3 imposes specific formal requirements — including that the instrument be a written promise or order — that go beyond the general concept. The Law Mind Contracts & Commercial Law Encyclopedia entries on negotiable instruments address these requirements in detail.
Historical Dictionary Support
Bouvier's Law Dictionary provides the only historical dictionary treatment available in the source corpus, and it is narrow: the entry consists almost entirely of the negative proposition that judgments and tax duplicates are not written instruments within the meaning of a pleading statute. This is useful as a data point but cannot be generalized into a comprehensive definition.
What Bouvier's misses: the entry does not address the criminal law usage, does not engage with the question of what affirmatively qualifies, and reflects nineteenth-century pleading practice that may not map cleanly onto modern procedural rules. Researchers should treat it as illustrative of one interpretive line rather than as authoritative on the term's full scope.
Jurisdictional Note
Jurisdictions vary significantly in how "written instrument" is defined within forgery statutes. Some states follow model penal code-influenced definitions that enumerate specific document types; others rely on common law conceptions closer to the Bouvier's formulation. Electronic records and digital documents present an ongoing definitional frontier that historical sources do not address.
Encyclopedia Cross-Reference
The Law Mind Contracts & Commercial Law Encyclopedia:
— Negotiable Instruments — Overview and UCC Article 3
— Negotiable Instruments — Requirements for Negotiability (S3-104)