Bezdůvodné obohacení

Under Czech law

Unjust enrichment is regulated by § 2991–§ 3005 of the Civil Code (Act No. 89/2012 Sb.). The classic situations listed in § 2991 odst. 2: performance without legal ground (paying a debt that does not exist), performance on a ground that later fell away (a contract found invalid or cancelled), and unlawful use of another's value — using someone's property, or having your debt paid by another. The enriched person returns what was gained; where that is impossible, monetary compensation follows (§ 2999), typically at the usual price of the benefit.

Good faith matters for scope: an honest recipient returns only what remains of the enrichment, a dishonest one everything including fruits (§ 3000–§ 3004). Claims limit in the standard three years, with §629 subjective / § 638 ten-year objective framing for enrichment claims.

A practical example

A company pays an invoice twice by mistake — once by the accountant, once through automated banking. The supplier refuses to return the second payment, pointing to "open items" from other projects. There is no legal ground for keeping the duplicate payment; a claim under § 2991 recovers it, plus late-payment interest once demand was made.

When you need a lawyer

When contracts collapse: invalid reservation agreements, cancelled property deals, or construction work done beyond a void contract all convert into enrichment claims, where quantifying "the benefit" and surviving the limitation objection decide the outcome.