Restitution, unjust enrichment and related claims

Unjust enrichment

Unjust enrichment is a cause of action which forms part of the law of obligations along with tort and contract. At its most basic, it is a claim based on an assertion that:

1. •

   the defendant has been enriched

2. •

   at the claimant’s expense, and

3. •

   it is unjust for the defendant to retain that enrichment/benefit

The concept of a claim in unjust enrichment developed out of a group of claims which were historically referred to as restitution or restitutionary claims. In the modern law unjust enrichment refers to the cause of action, whereas restitution is the remedy for a successful unjust enrichment claim—although sometimes the two terms are still used interchangeably.

For guidance on the elements of an unjust enrichment claim, see Practice Note: Unjust enrichment—elements of the claim.

In addition to the three elements of a claim in unjust enrichment set out above, it is also generally recognised that there is a fourth requirement—the absence of