UCL Faculty of Laws


Restitution of Unjust Enrichment (LAWS0105)

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By comparison with civil legal systems, English law was slow to recognise unjust enrichment as a source of private law rights and duties. That step was not taken until 1991. Since then a flood of restitutionary claims has surged through the courts.

In the 1990s the most important of these were prompted by the discovery that thousands of interest rate swap contracts entered by banks and local authorities were void; in the 2000s more claims were brought following CJEU declarations that parts of the UK tax regime were contrary to EU law.

The resolution of these claims has required the courts to decide many fundamental questions relating to the law of unjust enrichment, but many others remain to be decided. The cumulative value of the sums at stake has run into billions of pounds, and it is beyond question that a sound knowledge and understanding of the law in this area is essential for lawyers specialising in commercial litigation.


The module is arranged in line with the following precepts.

A claimant in unjust enrichment must show that the defendant was enriched, that his enrichment was gained at the claimant’s expense, and that his enrichment was unjust. When all three requirements are satisfied, the further question arises, whether there are any defences to the claim; if there are not, then the court must decide what remedy should be awarded.

The court must also consider whether the defendant’s enrichment is justified by an overriding source of rights such as statute or contract, as in this case recovery will be denied although the claimant would otherwise be entitled to restitution. 


Students who wish to take an advanced obligations course will enjoy this module. So will those with an interest in commercial law. The module has been designed to sit alongside the modules on Commercial Remedies and International and Commercial Trusts Law, and students can take all three of these in conjunction without any significant repetition of material.

Each week students are expected to read cases, textbook chapters and articles for class discussion and/or to prepare answers to problem questions which will be discussed in class. The teaching style is interactive: students are expected to ask and answer questions, make their own points and debate issues.

Students with an exceptionally strong knowledge and understanding of the obligations and property law principles of civil law jurisdictions have done well on the course and found it interesting and enjoyable. However, it is a conceptually challenging course and students who are not already skilled at distilling legal principles from a complex body of cases will find it difficult. It also helps students to have a strong knowledge and understanding of the common law principles of contract, property and trusts. 

Module syllabus

This module is subject to change.

  1. Unjust Enrichment and Restitution
  2. Enrichment I
  3. Enrichment II
  4. At the Claimant’s Expense I
  5. Mistake I
  6. Mistake II
  7. Undue Influence
  8. Failure of Consideration I
  9. Failure of Consideration II
  10. Problem Class
  11. Lack of Consent and Want of Authority I
  12. Lack of Consent and Want of Authority II
  13. Ultra Vires Payments and Receipts by Public Bodies
  14. Secondary Liability
  15. Defences I: Change of Position
  16. Defences II: Estoppel, Bona Fide Purchase, Illegality
  17. Justifying Grounds
  18. Remedies I
  19. Remedies II
  20. Revision

Recommended materials

The recommended textbook for the course is Andrew Burrows, The Law of Restitution 3rd edn (OUP, 2010), supplemented by reading in Charles Mitchell, Paul Mitchell and Stephen Watterson, Goff & Jones: The Law of Unjust Enrichment 9th edn (Sweet & Maxwell, 2016).

The latter is an expensive practitioner work but there is no need for students to buy it as they are provided with free access to an electronic version via the UCL Library’s Westlaw subscription.

Preliminary reading

Students who wish to find out more about the subject before making their module selections and/or to prepare for the course before term starts are advised to read the first chapter of Andrew Burrows’s textbook and/or the first chapter of Goff & Jones.

Other overviews of the subject which they might find helpful both before and during the course are Andrew Burrows, A Restatement of the English Law of Unjust Enrichment (OUP, 2012) and Charles Mitchell, ‘Unjust Enrichment’, chap 3 of Andrew Burrows (ed), Principles of the English Law of Obligations (OUP, 2015)

Key information

Module details
Credit value:30 credits (15 ECTS, 300 learning hours)
Convenor:Charles Mitchell
Other Teachers:Niamh Connolly
Teaching Delivery:20 x 2-hour weekly seminars, 10 seminars per term, Term One and Two
Who may enrol:LLM students only
Prerequisites:None (but students without a prior knowledge of common law principles of contract, property and trusts will find the course difficult and they are advised not to take it unless they have an exceptionally strong knowledge and understanding of their own jurisdiction's private law)
Must not be taken with:None
Qualifying module for:LLM in International Commercial Law
Practice Assessment:Opportunity for feedback on one optional practice essay per term (two in total)
Final Assessment:Exam (100%)