Legal Dictionary


Legal Definition of custom


  1. An old and general usage that has obtained the force of law

Definition of custom


    Middle English custume from Anglo-Norman custume from Old French costume from Vulgar Latin *consuetumen from Latin consuetudinem, accusative of consuetudo ("custom, habit") from consuescere ("to accustom"), inchoative form of consuere ("to be accustomed") from con- + suere ("to be accustomed"), perhaps from suus ("one's own, his own"); see consuetude. Displaced native Middle English wune, wone "custom, habit, practice" (from Old English wuna "custom, habit, practice, rite"), Middle English side, sid "custom" (from Old English sidu, sido "custom, note, manner"), Middle English cure "custom, choice, preference" (from Old English cyre "choice, choosing, free will").



custom (plural customs)

  1. Frequent repetition of the same act; way of acting common to many; ordinary manner; habitual practice; usage; method of doing or living.

    And teach customs which are not lawful. Acts xvi. 21.
    Moved beyond his custom, Gama said. Alfred Tennyson.
    A custom More honored in the breach than the observance. Shakespeare

  2. Habitual buying of goods; practice of frequenting, as a shop, manufactory, etc., for making purchases or giving orders; business support.

    Let him have your custom, but not your votes. - Joseph Addison.

  3. (law) Long-established practice, considered as unwritten law, and resting for authority on long consent; usage. See Usage, and Prescription.

    Usage is a fact. Custom is a law. There can be no custom without usage, though there may be usage without custom. Wharton.

  4. (obsolete) Familiar acquaintance; familiarity.

    Age can not wither her, nor custom stale Her infinite variety. Shakespeare

  5. The customary toll, tax, or tribute.

    Render, therefore, to all their dues: tribute to whom tribute is due; custom to whom custom. Rom. xiii. 7.

  6. (plurale tantum) Duties or tolls imposed by law on commodities, imported or exported.


  • fashion
  • habit
  • practice
  • usage

Derived terms

  • custom made

Further reading

Custom (law)

In law, custom can be described as the established patterns of behavior that can be objectively verified within a particular social setting. A claim can be carried out in defense of "what has always been done and accepted by law." Generally, customary law exists where:

  1. a certain legal practice is observed and
  2. the relevant actors consider it to be law (opinio juris).

Customary law and codification

The modern codification of civil law developed out of the customs, or coutumes of the Middle Ages, expressions of law that developed in particular communities and slowly collected and later written down by local jurists. Such customs acquired the force of law when they became the undisputed rule by which certain entitlements (rights) or obligations were regulated between members of a community. The Custom of Paris - the customary law that developed within the city of Paris - is an example of custom law.

Custom in torts

Custom is used in tort law to help determine negligence. Following or disregarding a custom is not determinative of negligence, but instead is an indication of possible best practices or alternatives to a particular action. The case R v. Boomsdale defines this principle with the courts ruling that Mr Boomsdale customary practice was not sufficient to be deemed an act of negligence.


  1. Wiktionary. Published under the Creative Commons Attribution/Share-Alike License.


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