不文律

• Reading: ふぶんりつ
• Romaji: fubunritsu
• Kanji breakdown: 不 (fu) — not, un-; 文 (bun) — writing, text; 律 (ritsu) — rule, law, regulation
• Pronunciation: /ɸɯbɯɴɾitsɯ/

Meaning

Unwritten law; unspoken rule; a convention or norm that functions as effectively binding without being formally codified.

A compound noun combining 不文 (unwritten) and 律 (rule, law). In political and legal contexts, 不文律 refers to constitutional conventions, customary practices, and informal norms that govern behaviour as powerfully as written statutes — particularly in systems like the United Kingdom's uncodified constitution. In everyday Japanese, it also describes the unspoken social rules that govern conduct within an organisation or community.

Examples

1. 英国の憲法は成文化されておらず、議会主権などの重要原則の多くが不文律として機能している。 The British constitution is not codified, and many of its important principles — such as parliamentary sovereignty — function as unwritten laws.
2. 先輩よりも先に退社しないという不文律が、この職場には依然として根強く残っている。 The unspoken rule of not leaving the office before one's seniors remains firmly entrenched in this workplace.
3. 国際社会においても、条約に明記されていない不文律が外交慣行を事実上規律している。 Even in international society, unwritten laws not explicitly stated in treaties effectively govern diplomatic practice.

Usage Guide

Context: law, politics, social norms, international relations

Tone: analytical

Origin & History

From 不文 (unwritten; 不 negation + 文 writing/text) and 律 (rule, regulation, law). The compound mirrors the Latin concept of lex non scripta (unwritten law), which entered Japanese legal vocabulary during the Meiji-era reception of Western legal systems.

Cultural Context

Era: Modern

Generation: Adults

Social background: Educated