Unjust enrichment under Greek law reverses a transfer of value that lacks lawful cause. It is not a general remedy for every perceived economic unfairness and does not automatically replace a contractual or tort claim that fails. Articles 904 et seq. of the Greek Civil Code impose specific requirements.

The Legal Foundation: Article 904 of the Civil Code

A person enriched without lawful cause from another’s property or at another’s expense must return the benefit. The obligation arises in particular where performance was made without a debt, for a purpose that did not materialise or ceased to exist, or for an unlawful or immoral purpose, subject to statutory limitations.

The remedy is restitutionary, not compensatory. Its purpose is to return the unjustified enrichment, not necessarily to compensate the claimant’s entire loss.

The claim requires the following elements:

Fault is not required. Where a valid contract or another lawful cause justifies the performance, unjust enrichment is not available merely because the transaction was disadvantageous to one party.

Why It Is Described as a Subsidiary Claim

The remedy has independent requirements. Where procedural law permits, it may be pleaded in the alternative if the principal contractual basis fails, for example because the contract is void. This does not mean that every rejected or time-barred claim automatically becomes an Article 904 claim.

Article 938 specifically provides that, even after a tort damages claim has become time-barred, the tortfeasor must return what they obtained under the rules of unjust enrichment. This remedy is limited to the benefit actually obtained and does not revive the full damages claim.

Typical Situations in Which It Arises

A claim may arise where:

Each category has distinct requirements. Payment or benefit alone is insufficient without examination of lawful cause.

How the Claim Is Pleaded in the Action

Where procedural law permits, unjust enrichment may be pleaded in the alternative or subsidiarily to a principal contractual or tort basis. The statement of claim must set out all facts establishing the enrichment, its connection with the claimant’s property or loss and the absence of lawful cause. Rejection of the primary basis does not automatically convert the action into a claim under Article 904.

Bank records, agreements, invoices, correspondence and accounting material may be decisive, depending on the case.

How the Defendant May Respond

Under Article 908, the recipient must return the item received or any substitute obtained from it, together with its fruits and anything obtained through its use. Where return in kind is impossible, monetary restitution is determined by the value of the enrichment retained.

Under Article 909, the obligation is extinguished to the extent that the recipient is no longer enriched when the claim is served. This defence is not automatic. From service of the claim, Article 910 applies the stricter consequences of Articles 346 and 348. Under Article 911, a recipient who knew or learned that no debt existed or that the cause was unlawful or immoral is liable as if proceedings had already been served. Where the expected purpose failed or later ceased, Article 912 imposes the corresponding enhanced liability from the time at which the recipient ought to have anticipated restitution.

The defendant may contend, among other matters, that:

• the enrichment is no longer retained, to the extent that Article 909 applies and subject to Articles 910–912;
• no enrichment arose, or its value is lower, particularly because counter-performance must be taken into account; or
• a valid contract, statutory rule or other lawful cause justifies retention of the performance.

Limitation period

As a rule, an unjust enrichment claim in Greece is subject to the general twenty-year limitation period in Article 249 unless a shorter special rule applies. Twenty years is not universal: the nature of the relationship, special legislation and the identity of the debtor—particularly the State—may lead to a different period.

Commencement, interruption and suspension must be assessed for the particular claim. Expiry of the principal claim does not, by itself, create a new twenty-year enrichment claim.

Frequently Asked Questions (FAQ)

Is unjust enrichment a damages claim?

No. It seeks restitution of the unjustified benefit rather than full compensation for loss.

Is fault required?

No. A benefit without lawful cause and the required link to the claimant must nevertheless be established.

Is the remedy available where a valid contract exists?

Generally not for a performance justified by that contract. It may be pleaded in the alternative where the validity or existence of the contractual basis is disputed.

Is the limitation period always twenty years?

No. Twenty years is the general rule, but special provisions may prescribe a shorter period.

What if the tort claim is time-barred?

Article 938 permits recovery of the benefit obtained by the tortfeasor; it does not fully revive the damages claim.

What if the recipient no longer retains the benefit?

Article 909 may apply, but the recipient’s knowledge and the stricter provisions of Articles 910 et seq. must be examined.

Conclusion

Unjust enrichment under Greek law may provide meaningful protection where the primary legal basis fails, but only if the distinct requirements of Articles 904 et seq. are properly pleaded and proven. It is not an automatic substitute for a rejected or time-barred claim.