Definition
A blanc seign (also spelled blanc seing) is a signed blank document — a paper bearing the signature of the signer at the bottom, left otherwise incomplete, and delivered to another person with authority to fill in the contents as that person sees fit, within the scope of any prior agreement between the parties. The signer, by delivering the blanc seign, binds himself in advance to whatever the holder inscribes above the signature, whether that takes the form of an obligation, an acquittance (discharge of a debt), a compromise, or another legal act.
The instrument functions as a species of anticipatory authorization: the signer's legal commitment attaches not when the document is completed, but when the blank paper is signed and surrendered. The holder's power to fill the instrument is personal and does not survive the holder's death — it cannot be exercised by the holder's heirs or assignees.
The term is principally a Louisiana civil-law concept, reflecting the state's French and Spanish legal heritage. It has no precise common-law equivalent, though it bears a functional resemblance to a power of attorney coupled with a pre-signed instrument.
Common Language
Modern common usage (Wiktionary): Not independently defined in standard modern English dictionaries. The French phrase blanc seing translates literally as "white signature" or "blank signature" — a signature affixed to a document whose content has yet to be filled in.
Historical common usage (Webster's 1913): Not listed as an English entry; recognized as a French legal term meaning a paper signed in blank, leaving the bearer authority to complete it.
Editorial note: The literal translation captures the physical reality of the instrument but misses its legal weight. In ordinary usage, signing a blank paper might suggest carelessness or incompleteness. In Louisiana civil law, it is a deliberate legal act conferring defined authority and creating binding obligation — the blankness is the mechanism, not the defect.
Common Confusion
Blanc seign is sometimes loosely equated with a power of attorney, but the two differ in important respects. A power of attorney is an explicit grant of authority to act on another's behalf, typically describing the scope of that authority in the instrument itself. A blanc seign leaves the content of the legal act entirely open, to be determined by the holder within any prior agreement. Additionally, Bouvier expressly notes that the power granted by a blanc seign is personal and dies with the holder — a limitation not necessarily implied by general agency principles. Researchers should also distinguish a blanc seign from a negotiable instrument signed in blank, which is governed by commercial paper law and carries different rules regarding transferability and holder rights.
Why It Matters in Research
Researchers working in Louisiana historical records — particularly from the nineteenth century — may encounter blanc seign in notarial acts, succession proceedings, mercantile disputes, and contract litigation. The term appears in early Louisiana reports precisely because courts were working out how civil-law concepts would function within an American judicial framework.
Two research traps deserve attention. First, the spelling varies across sources: Black's 1st edition uses blanc seign; Black's 2nd edition renders it blenc seign (likely a typographical error in the original); French-language sources use blanc seing. Corpus searches should account for all variants. Second, the personal nature of the authority — the rule that it dies with the holder — is a doctrinal point that Black's 1st edition omits but Bouvier preserves. Researchers relying solely on Black's for the rule of law may miss this limitation, which was directly at issue in litigation over estates and successions where a holder died before completing the instrument.
The sole case authority cited across all three source dictionaries is Musson v. U.S. Bank, 6 Mart. O.S. (La.) 718, an early Louisiana territorial-period decision. Researchers should treat this as the foundational primary source and examine subsequent Louisiana cases and civilian commentators for doctrinal development. The term largely disappears from American legal literature outside Louisiana after the mid-nineteenth century.
Historical Dictionary Support
All three source dictionaries — Black's 1st, Black's 2nd, and Bouvier's — converge on the same core definition and trace it to the same Louisiana authority. This uniformity suggests the dictionaries were drawing from a common source (likely Musson itself or an intermediate digest) rather than from independent analysis.
Bouvier adds the most substantive legal content: the rule that the power is personal and dies with the attorney (holder). This is a meaningful doctrinal addition absent from both editions of Black's, and it aligns with the civil-law principle that mandates and personal authorizations are extinguished by the death of the mandatary. Researchers should weight Bouvier's entry more heavily on this point.
None of the three dictionaries address what happens when a blanc seign is completed in excess of any prior agreement, or whether the signer has remedies against a holder who abuses the authority. These gaps reflect the limited American case law on the subject and would need to be filled by reference to French and Louisiana civilian sources.
Jurisdictional Note
Blanc seign is a civil-law instrument recognized in Louisiana. It has no recognized doctrinal status in common-law jurisdictions, which handle analogous situations through the law of agency, estoppel, and the rules governing incomplete negotiable instruments. Researchers applying Louisiana materials in federal courts or in other states should not assume the term carries legal force outside Louisiana's civilian tradition.