Definition
Parliamentum Insanum (Latin: "Mad Parliament") is the name applied by chroniclers to the Parliament assembled at Oxford in 1258, during the reign of Henry III (41 Hen. III). The assembly is historically distinguished by the Provisions of Oxford, a set of constitutional reforms forced upon the king by the barons, who arrived at the gathering under arms. The designation reflects both the turbulence of the proceedings and the contemporaneous judgment — at least from royalist quarters — that compelling a king to governance by baronial committee constituted a kind of political madness. The term is purely historical and descriptive; it identifies no legal doctrine, rule, or continuing institution.
Common Confusion
Parliamentum Insanum is sometimes loosely equated with the Provisions of Oxford themselves, but the terms are not interchangeable. The Parliamentum Insanum refers to the assembly as a historical event and its general character; the Provisions of Oxford are the specific constitutional documents that emerged from it. Separately, researchers should not conflate this assembly with the "Mad Parliament" occasionally referenced in later English constitutional commentary as a general epithet for any disordered legislative gathering. In the primary legal dictionary tradition, the term refers exclusively to the 1258 Oxford assembly.
Why It Matters in Research
This term appears in Law Mind's historical legal dictionaries as a compact identifier for a pivotal moment in medieval English constitutional history. Researchers encountering it in older legal texts, treatises, or abridgments should understand three things.
First, the entry is a gateway term. Neither Black's nor Bouvier's develops the constitutional significance of the assembly; they record the label and its immediate cause (the lords' armed attendance) without tracing consequences. A researcher who stops at the dictionary definition misses the principal reason the 1258 Oxford Parliament matters: it produced the Provisions of Oxford, which established the first formal council with supervisory power over the Crown and is regarded as a precursor to constitutional monarchy. Any serious research into this term should immediately move beyond the dictionary to primary chronicle sources and constitutional histories.
Second, the term's negative framing is royalist in origin. Calling the assembly "insane" reflects the perspective of those who viewed baronial constraint on royal prerogative as disorder. Researchers working on parliamentary sovereignty, the development of constitutional limits on the Crown, or the barons' reform movement of the mid-thirteenth century should treat the label itself as a historical artifact of political contestation, not a neutral descriptor.
Third, the term has no living legal application. It will not appear in modern statutes, regulations, or case law. Its research utility is confined to: (1) historical legal dictionaries and abridgments that use it as a cross-reference point; (2) medieval constitutional and parliamentary history; and (3) the broader arc of English legal development from Magna Carta through the eventual establishment of parliamentary supremacy. Within the Law Mind corpus, this entry connects most directly to materials on the history of Parliament, baronial reform movements, and the constitutional struggles of the Plantagenet era.
Historical Dictionary Support
Black's Law Dictionary and Bouvier's Law Dictionary are in close agreement, both recording the assembly as convened at Oxford under Henry III and attributing the "insane" designation to the armed presence of the lords and the perceived madness of their proceedings. Bouvier adds the cross-reference "See MAD," directing readers to a companion entry that likely addresses the broader label. Black's version adds a subsidiary note — apparently from Cowell — identifying a hill where courts were anciently held, though this detail appears to be a typographical or editorial artifact of the dictionary's layout rather than substantive commentary on the Parliamentum Insanum itself; researchers should not treat it as directly related to the 1258 assembly.
Neither dictionary provides constitutional context, names the Provisions of Oxford, or situates the assembly within the broader baronial reform movement. Both entries are purely descriptive and historically thin. Jacob's Law Dictionary, cited by Bouvier, is the likely common ancestor for the formulation both sources share. Historical dictionaries of this era frequently perpetuated the royalist characterization without critical analysis, which is itself a data point for researchers studying how legal reference works shaped — or reflected — constitutional attitudes toward parliamentary authority.
Jurisdictional Note
This term is specific to English constitutional and parliamentary history and has no application in American, Scottish, or other common law jurisdictions except as a historical reference.
Encyclopedia Cross-Reference
See Law Mind Encyclopedia: History of Parliament; Provisions of Oxford; Constitutional Development Under the Plantagenets.