Juristic Acts Contrary to Public Policy or Good Morals

Plain-language explanation

Article 90 of the Civil Code establishes a simple but powerful rule: any juristic act (contract, agreement, unilateral legal act, etc.) that violates "public order or good morals" is void. Even if both parties freely agreed and signed a document, if the substance of the deal is seriously offensive to societal ethics or public order, the law treats it as if it never had legal effect from the start.

Though the wording is abstract, in practice this article functions as a "last resort" safety net. Even when no specific statute explicitly bans a particular clause or arrangement, courts can rely on Article 90 to void an entire contract or a problematic clause within it. Common examples include extremely excessive penalty clauses, contracts that unduly strip workers of basic rights, agreements to facilitate bribery or bid-rigging, usurious lending terms that are grossly unfair, and clauses that embody illegal discrimination.

For business owners and lawyers drafting contracts, this article is a critical reminder that freedom of contract has limits. A clause that looks technically legal on its face — such as an unreasonably one-sided non-compete, an exploitative interest rate, or an oppressive franchise term — can later be challenged and invalidated by a court or counterparty under Article 90. This is especially relevant in employment agreements, franchise agreements, loan agreements, and lease contracts where bargaining power is unequal. Businesses should proactively review contract terms for fairness, not just legality under specific statutes, to avoid the risk of unenforceability down the line.

日本語での解説

Common scenarios

• ▸フランチャイズ契約における加盟店に著しく不利な違約金条項の有効性が争われる場合
• ▸金銭消費貸借契約で著しく高い利息が暴利行為として無効と主張される場合
• ▸雇用契約で労働者の退職後の競業避止義務が過度に広範囲・長期間で無効とされる場合
• ▸談合や贈収賄を目的とした業者間の合意が公序良俗違反で無効とされる場合
• ▸不動産賃貸借契約における差別的な入居条件が公序良俗違反として問題になる場合