Definition
A procedural mechanism used in deliberative assemblies to end debate and bring a matter to a vote. Cloture functions as a brake on unlimited debate: once successfully invoked, it cuts off further discussion and forces a final vote on the pending question.
In the United States Senate, cloture has particular constitutional and political significance. Under Senate Rule XXII, invoking cloture requires a three-fifths affirmative vote of all senators duly chosen and sworn (typically 60 of 100 senators), though a simple majority suffices for certain matters including nominations following rule changes adopted in 2013 and 2017. Once cloture is invoked, total additional debate is capped at 30 hours. The mechanism is the primary — and often only — tool for ending a filibuster.
In parliamentary assemblies more broadly, cloture (or closure) is the generic term for any procedure that terminates debate by vote of the body. Specific mechanics vary by governing rules.
Common Language
Modern common usage (Wiktionary): In legislative assemblies that permit unlimited debate (that is, a filibuster), a motion, procedure, or rule by which debate is ended so that a vote may be taken on the matter. For example, in the United States Senate, a three-fifths majority vote of the body is required to invoke cloture and terminate debate.
Historical common usage (Webster's 1913): See Closure, 5. (Webster's treats cloture as a variant spelling of "closure" in its parliamentary sense, without separate elaboration.)
The common usage here is unusually close to the legal/parliamentary meaning, but researchers should note one gap: popular usage frequently conflates cloture with simply "ending debate," obscuring that it is a specific procedural vote with its own threshold requirements, timing rules, and strategic implications distinct from a routine motion to proceed.
Common Confusion
Cloture is sometimes confused with the previous question motion, which serves a similar debate-ending function in many deliberative bodies but operates differently. In the U.S. House of Representatives, the previous question is the standard debate-ending tool and requires only a simple majority; cloture as a Senate institution does not apply in the House. Bouvier's specifically notes that cloture "is generally effected by moving the previous question," reflecting historical parliamentary practice, but in modern U.S. Senate usage cloture and the previous question are distinct procedures. Researchers working with older parliamentary manuals must be careful not to treat the terms as interchangeable.
Cloture should also be distinguished from unanimous consent agreements, which can achieve similar results by agreement of all members without a formal cloture vote.
Why It Matters in Research
The most significant research trap is Bouvier's note that cloture "is not recognized in the senate of the United States" — a statement that was accurate when written but became obsolete after the Senate adopted Rule XXII in 1917 in response to filibustering of World War I preparedness legislation. Any historical source predating 1917 will reflect the Senate's pre-cloture posture, and sources from 1917 through 1975 will reflect the original two-thirds threshold, which was subsequently reduced to three-fifths. Researchers using pre-1975 materials should note that the vote threshold was materially different.
The spelling variation matters for corpus searching. American sources predominantly use cloture; British and Commonwealth parliamentary sources use closure. Because the concept entered English parliamentary practice in 1882 and was imported into American usage, early American sources may use either spelling interchangeably. A search limited to "cloture" may miss relevant closure entries in older treatises and parliamentary manuals.
Roberts' Rules of Order — cited in Bouvier's — remains a widely used governance document for non-legislative deliberative bodies, but its treatment of debate-ending procedures differs from Senate Rule XXII. Researchers analyzing organizational governance, corporate bodies, or state legislative chambers should confirm which procedural rules actually govern before applying federal Senate standards.
For modern Senate research, the distinction between the 60-vote cloture threshold for legislation and the simple-majority threshold now applicable to nominations is essential context that no historical dictionary source captures. These rule changes (the so-called nuclear option, invoked in 2013 for executive and most judicial nominations and in 2017 for Supreme Court nominations) fundamentally altered how cloture functions in practice.
Historical Dictionary Support
All three historical sources — both editions of Black's and Bouvier's — agree on the core definition: cloture is the procedure in deliberative assemblies whereby debate is closed, introduced in the English Parliament in the session of 1882. The uniformity is notable, suggesting the term had a settled parliamentary meaning at the time of writing.
Bouvier's adds the most useful detail, citing Wharton's legal dictionary and Roberts' Rules of Order, and noting that cloture is "generally effected by moving the previous question." The Bouvier's entry also contains the historically significant observation that the motion "is not recognized in the senate of the United States" — a statement that dates the entry to pre-1917 and serves as a reliable signal of the source's age for corpus researchers.
The historical dictionaries say nothing about vote thresholds, timing limits on post-cloture debate, or the interaction between cloture and the filibuster as a named institution. These are entirely modern developments that require contemporary sources.
One anomaly in the Black's Law Dictionary entry as it appears in the source material: the cloture definition concludes with text about cloud on title ("applicable to the estate in question. A conveyance, mortgage, judgment, tax-levy, etc., may all, in proper cases, constitute a cloud on title"). This appears to be a typographical bleed from an adjacent entry and should not be read as part of the cloture definition.
Jurisdictional Note
Cloture as a formal institution is primarily significant at the federal level in the United States Senate. State legislative chambers vary widely — many use the previous question motion or simple majority votes to end debate and do not have a cloture rule. Researchers analyzing state legislative history should verify the specific chamber's procedural rules rather than assuming Senate Rule XXII standards apply.
Encyclopedia Cross-Reference
See Law Mind Encyclopedia — Legislative Procedure; Filibuster; Senate Rules