Definition
Non scripto (also rendered *jus non scriptum* or *lex non scripta*) is a Latin phrase meaning "not written." In legal usage, it describes unwritten law — that body of legal rules and obligations that derives its authority not from formal legislative enactment or recorded statute, but from custom, usage, tradition, and long-standing practice. The phrase is the counterpart to *jus scriptum* (written law) and forms one half of the classical Roman and common law division of all law into written and unwritten categories.
In the common law tradition, *lex non scripta* became a near-synonym for the common law itself — law that exists in judicial decisions, immemorial custom, and accepted practice rather than in the text of a statute. Blackstone's *Commentaries* used the distinction prominently: the *lex scripta* being parliamentary statutes, the *lex non scripta* being the unwritten customary law transmitted through courts and community practice. The phrase thus carries both a descriptive meaning (law not contained in a written instrument) and a conceptual one (law whose legitimacy flows from custom and consent rather than sovereign command).
Common Confusion
Non scripto is sometimes used loosely as a synonym for *customary law* or even *natural law*, but these are distinct concepts. Customary law is one species of unwritten law; natural law is a philosophical category grounded in reason or morality rather than practice. Not all unwritten law is customary (judicial common law, for instance, is unwritten in the *non scripto* sense but is not custom in the strict sense), and unwritten law is not coextensive with natural law. Researchers should resist collapsing these categories when analyzing historical arguments about the authority of unwritten legal norms.
Why It Matters in Research
Researchers working in historical common law materials will encounter *non scripto* and *lex non scripta* as terms of art that do real conceptual work, not mere ornamental Latin. The distinction matters for several navigational reasons.
First, temporal context shifts the weight of the term. In pre-modern legal writing, the written/unwritten division tracked the Roman distinction between imperial edicts (*scripta*) and customary provincial law (*non scripta*). In English common law sources from Blackstone forward, *lex non scripta* is essentially coextensive with the common law as a whole — a much broader and more substantive claim than simply "there is no statute on this point."
Second, the term can obscure what it describes. "Unwritten" is historically misleading: common law rules were extensively recorded in Year Books, case reports, and treatises. The *non scripto* designation means the law did not originate in a written legislative act, not that it was never committed to writing. Researchers reading primary sources should not mistake the label for a claim about documentation.
Third, the phrase appears in discussions of custom as a source of law, constitutional theory (particularly in arguments about unwritten constitutional principles), and conflict of laws (where courts historically distinguished between statutory rules of a foreign jurisdiction and its customary or common law). Each context carries different analytical freight, and a researcher tracking the term across these domains should expect the argument structure to shift accordingly.
Fourth, the Law Mind corpus contains historical sources that use the Roman civil law vocabulary (*jus scriptum / jus non scriptum*) interchangeably with the English common law vocabulary (*lex scripta / lex non scripta*). These are cognate but not identical traditions, and conflating their doctrinal frameworks can mislead.
Historical Dictionary Support
Bouvier's Law Dictionary does not contain a dedicated entry for *non scripto* in the source material provided. The supplied Bouvier's entry — for *jus oneris ferendi*, a Roman urban servitude — appears to be a cataloging artifact and has no bearing on this term.
The absence of a standalone Bouvier's entry is itself informative. *Non scripto* functions more as a modifier or descriptive phrase than as a discrete legal doctrine with its own elements. Historical legal dictionaries typically treat it within broader entries on custom, common law, or the classification of law. Researchers should look to entries on *lex non scripta*, *common law*, *custom*, and *jus scriptum* in Bouvier's and its contemporaries for the fuller treatment. Blackstone's *Commentaries on the Laws of England* (Book I, Introduction, Section III) remains the canonical English-language source for the written/unwritten law distinction and is the practical reference point for most 18th- and 19th-century uses of the term in common law jurisdictions.