Definition
In old Law French legal usage, *fous* means fools or persons of unsound mind — individuals incapable of legal action by reason of mental deficiency. The term appears in historical English legal texts as a classification of persons lacking legal capacity. It is closely associated with the companion phrase *fous nastres* (natural or born fools), denoting persons born without intellectual capacity, as distinguished from those who lost mental capacity later in life.
Common Language
Modern common usage (Wiktionary): *Fou* (singular) is a French adjective meaning mad, crazy, or foolish. The plural *fous* carries the same sense in modern French.
Historical common usage (Webster's 1913): Webster's 1913 does not separately list *fous* as an English entry; the word remained a foreign-language term in English legal usage rather than passing into common English vocabulary.
Editorial note: The ordinary French meaning of *fous* as merely "crazy" or "foolish" understates the legal weight of the term. In historical English law, classification as *fous* or *fous nastres* was a formal legal determination with consequences for property rights, contractual capacity, and the wardship powers of the Crown — not simply a colloquial judgment about a person's behavior or temperament.
Recognized Forms
/SUBTYPES
*Fous nastres* (natural or born fools): Persons born without intellectual capacity. Distinguished in early English law from those who had capacity and lost it — the latter category governed by different legal rules (see *non compos mentis* and the distinction between idiocy and lunacy).
Why It Matters in Research
Researchers working in medieval and early modern English legal sources will encounter *fous* and *fous nastres* in texts heavily influenced by Law French, particularly in materials touching on guardianship, property, and the prerogative rights of the Crown over persons of unsound mind. The term signals a formal legal classification, not merely a descriptive characterization.
The critical research trap is conflating the two historical categories: *fous nastres* (born fools, corresponding to what later law would call idiots) and persons who became mentally incapacitated after birth (lunatics). English law treated these categories differently with respect to Crown prerogative and the management of their estates. Bracton, Britton, and Fitzherbert each address these distinctions, and sources that use *fous* without qualification may be referring specifically to the born-fool category or using the term more loosely to cover all persons of unsound mind — context determines which.
Because *fous* is a Law French term, it will appear almost exclusively in sources predating the gradual displacement of Law French from English legal writing (roughly completed by the eighteenth century). Modern legal sources will not use the term; researchers tracing the doctrinal lineage of mental incapacity law must translate forward through *idiot*, *lunatic*, *non compos mentis*, and eventually into modern competency and guardianship frameworks.
Historical Dictionary Support
Burrill's Law Dictionary defines *fous* concisely as "fools" in Law French, with *fous nastres* glossed as "natural or born fools," citing Britton chapter 10. Burrill's treatment is minimal but accurate in pointing researchers toward Britton as the primary source for this terminology in early English legal literature.
The brevity of Burrill's entry reflects the limited circulation of the term even within legal dictionaries — *fous* is a term of art embedded in a specific stratum of Law French legal writing rather than a term with sustained doctrinal development under its own name. Later legal dictionaries largely absorbed its meaning under entries for *idiot*, *lunacy*, and *non compos mentis*, where the substantive law was developed at greater length.
Burrill does not address the procedural or prerogative dimensions of the classification — the Crown's role in managing the property of *fous nastres* — which Britton and later commentators treat more fully.
Jurisdictional Note
The term belongs exclusively to the English common law tradition as received through Law French. It has no independent currency in Scottish, civilian, or American legal sources, though the underlying doctrinal distinctions it encodes — between congenital incapacity and acquired incapacity — carried forward into American common law under different terminology.