Definition
In law, "arbitrarily" describes the manner in which a decision, ruling, or exercise of discretion is made when it lacks a rational basis, is unsupported by facts or law, or reflects the decision-maker's will rather than a reasoned judgment. A decision made arbitrarily is one that cannot be justified by reference to applicable standards, evidence, or legal principle.
The term appears most frequently in two related contexts:
1. Administrative and regulatory law: A governmental body or official acts arbitrarily when it exercises discretionary authority without adequate factual foundation, without applying consistent standards, or in a manner that is capricious or unreasonable. Courts reviewing agency action ask whether the decision was "arbitrary and capricious" — a standard that demands at minimum that the decision-maker considered relevant factors and reached a rational conclusion.
2. Constitutional and due process law: Government action that is arbitrary in the constitutional sense violates substantive due process. Here the term carries additional weight: not merely unreasonable in a procedural sense, but so lacking in rational justification as to be an abuse of governmental power.
Common Language
Modern common usage (Wiktionary): "In an arbitrary manner. To an arbitrary degree."
Historical common usage (Webster's 1913): "In an arbitrary manner; by will only; despotically; absolutely."
The common meaning captures the essence well enough that the legal meaning rarely surprises non-lawyers — but the gap matters in legal research. In ordinary usage, "arbitrarily" often implies mere randomness or personal preference with no strong normative charge. In law, "arbitrarily" is a term of art with a defined threshold: it signals an actionable defect in the exercise of legal authority, sufficient to void a decision or sustain an appeal. The word does not merely describe how something felt to the losing party; it invokes a standard of review.
Common Confusion
"Arbitrarily" is frequently paired with "capriciously" in statutes and judicial opinions — the phrase "arbitrary and capricious" is so common it functions almost as a single term. Researchers should be aware that courts do not always distinguish the two words with precision. Some opinions treat them as synonyms; others assign "arbitrary" to decisions without rational basis and "capricious" to decisions made on sudden impulse or without consistent application. Neither word alone carries a fixed technical meaning across all jurisdictions or all eras of case law.
Why It Matters in Research
The term is most dangerous in historical sources because its threshold shifts over time. Nineteenth-century courts tolerated wider administrative discretion, and what passed as a defensible exercise of authority in 1890 would often be condemned as arbitrary under modern administrative law standards. Researchers examining licensing decisions, regulatory actions, or municipal exercises of power in older materials should not assume that the contemporary meaning of "arbitrarily" maps cleanly onto the historical record.
The saloon-license illustration in Bouvier reflects an important early application: courts were beginning to enforce limits on local licensing boards that had operated with virtually unchecked discretion. That trajectory — from near-absolute discretion to reviewable action — defines the historical arc of the term in American public law.
In constitutional research, "arbitrary" bridges due process doctrine and equal protection analysis. A law or government act challenged as arbitrary may implicate either or both, and the controlling standard (rational basis, heightened scrutiny, or strict scrutiny) determines what "arbitrary" must mean in context. Researchers should identify which doctrine is in play before relying on case language that uses the term loosely.
For corpus researchers: the word appears in statutes, appellate opinions, jury instructions, and constitutional commentary, but its meaning is always downstream of the standard of review being applied. Always identify the procedural or constitutional framework before treating "arbitrarily" as a fixed point.
Historical Dictionary Support
Bouvier's sole entry grounds the term in a Kentucky appellate case involving a licensing board's refusal to grant a saloon license. The entry's value is not in its brevity but in what it reveals about how early courts understood reviewability: the word "arbitrarily" in a statute was construed as creating a right of appeal that would not otherwise exist. This shows the term functioning as a jurisdictional trigger — the presence of the word in a statute was itself legally operative, not merely descriptive.
Bouvier does not attempt a general definition, which reflects the term's nature: "arbitrarily" is a relational word that draws its meaning from the standard against which action is measured. What historical sources miss is the modern administrative law architecture — the APA framework, the Chevron and post-Chevron doctrine, the "hard look" review standard — that gives the term its current structural significance. Researchers working in pre-APA materials will find a thinner, more case-specific concept.
Jurisdictional Note
The arbitrary-and-capricious standard is codified in federal administrative law and in most state administrative procedure acts, but the stringency of review varies. Some states apply a deferential standard close to the federal rational-basis test; others impose a more searching inquiry. In constitutional litigation, the federal standard of review for substantive due process claims turns on whether a fundamental right or suspect class is involved, which affects how demanding the "arbitrary" threshold becomes.
Encyclopedia Cross-Reference
See Law Mind Encyclopedia: Administrative Discretion; Judicial Review of Agency Action; Arbitrary and Capricious Standard; Substantive Due Process.